Child anxiety about becoming ill

[LVJ1]

My daughter aged 11 has recently started to become anxious about becoming unwell. Every day she seems to have a new concern. Examples are things like -
“do I look pale, I think I do maybe I’m unwell, is this normal to be pale”
She ate a kinder bueno and then thought she might be allergic to nuts and go into anaphylactic shock (she has never been nor does she know anyone who is allergic to nuts)
She had a small ache in her side after spending a long time on the trampoline so decided she must have appendicitis.
If she becomes slightly warm she worries it’s a temperature and she’s going to be ill.
we are due to go on holiday and she thinks if she gets bites she will catch malaria.
I have no idea where this has come from, generally as a family we are fit, healthy and relaxed with regards health.
Im not sure if this is a phase that will pass or something which may get worse if not managed correctly.
Any advice/experiences would be appreciated.

SDC were like this. They have both since been diagnosed with autism and ADHD, as teen girls. Health anxiety seems to be a massive issue for them. One particularly would ask if they would be sick, over and over again, especially at bedtime. They were also obsessed with trying to work out how they’d got ill; eg, X was coughing the other day, I’ve caught it from them. No real advice, sorry.

My DC had health anxiety quite bad. I really recommend you read this book: Breaking free of child anxiety and OCD (Amazon/Audible)

My child, now an adult, has this. I’m sure it was caused by the fact that as a baby and toddler, she actually did have a lot of hospital visits and investigations for various things to do with poor growth and small stature. Then as a teen, she had more due to migraines and vision problems. It’s almost like it’s hard-wired into her now. My other DC aren’t like this at all.