“After we called the ambulance and saw Mum off to hospital, did we just go back to bed?”

“No, we watched a film.”

This is a conversation I had with my sister a few weeks ago. This is when I realised, 12 years after the fact, that once we’d dealt with the emergency of finding Mum unconscious on the bathroom floor, I must have gone into shock.

Like most spoiled teenagers returning from their first year at university, I thought I was in for a summer of having meals cooked for me, while my mum resumed laundry duties. I was wrong. And not because my lovely mum wouldn’t do those things for me, but because she couldn’t. She had collapsed, after having spent the day in bed with a migraine.

Migraines weren’t completely out of the ordinary for Mum, so we hadn’t thought much of it until around midnight, when she went to the bathroom. There was a bang, and then the sound of my dad racing down the landing, forcing the bathroom door open and shouting for our help.

I remember so clearly calling the ambulance; they had a lot of questions. Younger readers won’t necessarily understand this but back then many homes had telephones tied to their walls by little wires. You couldn’t take them out of the rooms they were in and ours, weirdly, was not in the bathroom. So to get the answers to the operator’s questions I had to keep running to the landing to ask Dad. Dad was pale and concentrating on keeping Mum breathing.

I remember so clearly Dad snapping: “Stop wasting time with these questions and just send the ambulance.”

I remember so clearly pacing out to the main road, in my dressing gown and slippers, to wave the ambulance down and direct it to our tucked-away home at the back of a housing estate.

And then … once I’d done my job, and she was in the best possible hands, I remember nothing. I don’t remember the film we watched, or going to bed, or the cups of tea we just must have had. We were English people in a tough spot, after all.

The next day I learned that Mum had something called viral encephalitis. This was a string of sounds I had not heard before. It’s an inflammation of the brain that needs hospital treatment and can result in serious brain damage. Mum was in and out of consciousness in the hospital bed and still relapsing into fits occasionally. I’m extremely fortunate that I only experienced the reality of living in a traumatic situation at 19. Some people are born into that, but for me this was where I learned that when drama happens, the mundane doesn’t stop.

Mum was lying in a hospital bed, making progress, but without a memory. My siblings and I sat around the bed as she looked my dad in the eye and asked who we were. I suppose I had always thought that when things like this happen, some sort of invisible service steps in to take care of all the little things in life that need doing so you can focus on the bigger picture. It does not. We reminded our mum that we were her children and then we went home and I cooked us spaghetti.

Dad was a self-employed builder working on a contract that needed to be finished by the end of the summer holidays or his business would be in trouble. There was no clause in the contract for the school he was building to “not need a toilet block” if there was a family medical emergency. The time off to visit Mum was making the deadline tight, so I found myself working as a builder’s assistant, using a spirit level instead of partying at uni.

While Dad split his time between the hospital and the building site, I took over caring for my siblings. I’d passed my driving test in a Nissan Micra at 17 and not driven since. Suddenly, I was in charge of a seven-seater Volkswagen Sharan, taking two kids to Clarks to get new school shoes. It was quite a coming of age. I hated that minibus. It was so bulky, and seemed to seek out collisions with things I couldn’t explain to Dad.

I remember trying to park it once. It was going badly – like trying to get your hips back into November’s jeans come January. It was taking me so long a whole family had stopped what they were doing to watch. Eventually, Dad came along and knocked on the window. I wound it down, cheeks burning. He smiled, and said: “I’ve found you a bigger space.” I remember so vividly the Paolo Nutini album we listened to a lot in that car, that summer.

We got to keep our mum, and, slowly, she got most of her vocabulary and memory back. I remember all the bits of that summer where I was needed so clearly, but had no realisation, until that conversation with my sister, that in the in-between times, I was somewhere else entirely.

Pivot by Laura Lexx (John Murray Press, £16.99). To support The Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.