I am a professional bodybuilder and was on my way to the gym, around midday, in November 2016, in my home town of Stoke-on-Trent. I typically work out for five or six hours a day, and can bench-press 180kg. As I approached my car, I saw there were lots of ladybirds on the door and roof. I picked one up to take a closer look. As a kid, I always loved ladybirds, but these didn’t look like normal ones; they were a different shape, almost twice as big and black with orange dots. I let them walk over my hand, then brushed them off, got in the car and didn’t think anything more about it.

Not long after, I felt a sharp pain on my left-hand side, around my neck. At the gym I told my mate that something didn’t feel right. The pain had spread to my left foot and it felt as if it was burning. He told me to get a grip and stop moaning. I did my normal workout and then drove for a couple of hours to Milton Keynes, where I was due to present trophies to winners of a bodybuilding competition the next day.

I arrived around 7pm and checked into a hotel. My foot was still hurting, but I thought it might be from all the driving. Later, I couldn’t sleep. In the early hours, I looked at my foot: it was very badly swollen and looked like a giant’s. I was shocked. I thought maybe I’d dropped something on it or knocked it at the gym. I knew I had to get to a hospital, but I couldn’t walk.

I called reception and the concierge helped me out of the room and took me downstairs in a luggage trolley. I got a taxi to the hospital, where they took an x-ray and did a blood test. They weren’t sure what was wrong, but advised me to take antibiotics and anti-inflammatories, as they thought I might be having an allergic reaction. I left the hospital around 7am, with a crutch, made a quick appearance at the bodybuilding competition, then managed to drive home, still in a lot of pain.

By the evening my foot was black and a friend rushed me to the Royal Stoke University hospital. After more blood tests and more confusion, a consultant from another hospital was called. He arrived and told me to strip off, so he could examine every part of my body. He noticed that the left side of my groin was swollen. He said my body was trying to fight an infection. I was 31 and very fit. I’d never been ill in my life.

He asked if I’d touched anything unusual or cut myself recently. I said no. He asked if I’d been near any chemicals. No. Had I been near any insects? That’s when I remembered. I thought mentioning the ladybirds would sound stupid, but I told him anyway. He asked me what kind of ladybirds they were – did they look different? I explained the colour and the size. He said they sounded like harlequin ladybirds, an invasive species. I’d never heard of them and was shocked to learn they carry a fungal disease in their saliva.

The doctor diagnosed severe sepsis, caused by a ladybird bite. I didn’t even know ladybirds could bite. He told me the saliva had got under my skin and into my system, and I needed to take very strong antibiotics and morphine. There were a lot of nasty side-effects, but I was lucky: one out of three people die from the severity of the sepsis I had. There was a chance they’d have had to amputate my leg, which terrified me. It would have ruined my life.

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Afterwards, I couldn’t walk properly for a long time and was in a lot of pain. I couldn’t eat – my weight dropped from 100kg to 75kg, which for a bodybuilder is a very bad thing. It really messed me up and it took me a long time to recover.

Since then, I’ve had a phobia of ladybirds. I don’t mind snakes or spiders or wasps, and I’m not scared of any other kinds of insect, but ladybirds – I just don’t want to be near them. I know I’m so much bigger than they are, but it was such a terrible experience. Before this happened, I used to think they were cute and harmless; I used to play with them as a child. Now, if I see a ladybird, I run.

• As told to Sophie Haydock

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