Happiness and sunlight are inextricably intertwined; they are perfect bedfellows. Everyone looks forward to summer – when the clocks go forward, you can practically hear the collective sigh of relief. Summertime means picnics in the park, summer dresses and sandals, drinks by the river. It means warmth, joy and romance.

Last year, I started to get a rash when I was running. I loved running in the park; it was my coping mechanism for times when I felt sad or stressed. The rash would appear on the exposed parts of my body – my arms and hands, shoulders, and legs. It was uncomfortable, and it would turn into hives. Usually it would disappear within about an hour. I didn’t really understand what was happening, I thought that it might be a topical allergy to pollen, so I’d just down some antihistamines and they seemed to help.

One day I was showering at the lido, having been for a swim, and I started to become very hot and itchy. When I got out of the shower, there was a clear delineation of my exposed and unexposed flesh – my swimming costume still visible on my naked body – a boundary between soft, pale skin, and angry, red flesh. I started to feel faint.

A friend I was with hurried away to get me some water. Two members of staff followed her back into the changing room; they were freaking out about my reaction, and wanted to call an ambulance. One of them put on a latex glove, which struck me as bizarre. It turned out she wanted to feel my temperature without having skin-to-skin contact, but seeing someone snap on a latex glove only added to my rising feeling of panic.

I remember desperately trying to put on my knickers as a room full of people gawped at me, while my mind filled with visions of being carted out on a stretcher naked and covered in hives. I imagined people crowding round as my throat closed up, with – why not? – a few ex-lovers and colleagues thrown in for good measure. I’ve always loved the grand and dramatic, and I prepared myself to receive the Oscar for best public humiliation.

In the end, they didn’t call an ambulance. I managed to get dressed, and my friend administered the classic British remedy – tea and cake. I sat in the cafe shivering and shaking, my body’s reaction to the physical duress. I think I came pretty close to anaphylaxis that day.

Following that episode, I was diagnosed with a condition called solar urticaria, which means I’m allergic to sunlight. Mostly, when I tell people I’m allergic to the sun, they laugh because they think I’m joking – that I burn easily, or that I’m not too keen on sunny weather. But I’m literally allergic to sunlight.

The worst thing about my allergy is how unpredictable it is. Some days there are small patches of rash on my exposed skin, other days it’s everywhere, and I feel like I’m going to pass out. It’s not always the sunniest days, either. The UV index can be high even when it’s not particularly hot.

Last summer, during the months that I waited for an appointment with a dermatologist, I started to fear going outside. I got a kind of inverse Sad. Seasonal Affective Disorder can make people feel depressed as the days get shorter and darker; I got more depressed as the days got longer and brighter. I started to think about killing myself. It would be easy – I could just stand in the sun.

One seemingly cloudy day, I had a bad reaction while walking along the South Bank. I took cover in the Tate Modern. As I stood in front of Picasso’s Nude Woman With Necklace, I thought to myself: if I have to go now, at least it will be in front of something beautiful. I prayed that her gushing life force would save me.

Before all of this, when I was having a bad day at work, I used to look at the photos on holiday websites of infinity pools and beach bars, of someone sipping from a coconut on a sun lounger. Those photos make me anxious now. I preemptively feel my skin start to itch and burn. I have nightmares about being stranded in the sunlight. The idea of travelling is much less appealing now that I have to take strong antihistamines and wear factor 30+ even in the British winter. When just leaving the house feels like a military operation, leaving the country can feel a bit overwhelming. And worse than being pickpocketed for my holiday cash or my passport – what if someone took my antihistamines?

I’m still waiting for UV testing, where you are tested for the specific wavelengths of light that affect you, and how long it takes you to react. Some people’s allergy extends to the wavelength that emanates from computer screens and electric lights. I dread mine worsening, not being able to go out in the daytime, or having to black out all the windows. Imagine if you couldn’t turn on the light in the bathroom on a dark morning? It’s such a socially isolating affliction.

At first I felt like my sunlight allergy took away my coping mechanisms – but I’m discovering that I can run in long-sleeved tops and factor 50, and that you can buy swimming leggings and socks to cover up. In summer my look is “Victorian goth” – think long, black gloves and a parasol. I try to make it more like a fashion choice and less like an affliction. I think that if I can find the fun, then maybe it won’t be quite so depressing.

Doctors don’t always know very much about solar urticaria, and their reactions are not always sympathetic. One GP told me that I’d probably need an EpiPen, but, in the meantime, if I felt my throat closing up, just to call 999. “How will I know?” I asked. “Don’t worry,” she said, “you’ll have an impending sense of doom”. How very reassuring. Another time, a dermatologist asked me why I was so bothered by my condition: “It’s better to put sunscreen on every day anyway.” I was so angry I couldn’t look at her.

As well as antihistamines, there are other treatments. There’s a process called “skin hardening” that works on the same principle as a vaccine – exposing you to small doses of UV can help you to build up an immunity. There’s also a relatively new drug called Xolair which was invented for asthmatics but has been effective on many patients with solar urticaria. At the moment I’m dreading summer – but I hope there will be some light at the end of the tunnel. Or in my case, shade.