Why can’t I stop thinking about it?

I’d always been a healthy kid until I was about 12 I got seriously ill out of nowhere, I spent 4 years in and out of hospital and almost had brain surgery, I had 7 lumbar punctures and I was on medication that messed up my blood so I constantly had to have blood drawn. It screwed with me a lot and I felt suicidal because I couldn’t cope with it, they didn’t know what caused it but after the 4 years of what felt like torture it went away suddenly and now I’m 21 and back to perfect health as if there was nothing ever wrong, which I’m grateful for, but it leaves me in a state of ‘what the fuck just happened’ I developed anxiety and depression because of it which I managed by myself because no therapist (except for one who I love and grateful for) helped me. I no longer deal with the depression or anxiety but what happened still plays on my mind and I can’t step foot in or near a hospital or doctors office, they terrify me now, I can’t watch medical shows, I won’t let anyone touch my back where the lumbar punctures were done because it makes me physically feel sick and ill. I’ve had therapy for it but they gave up each time after two weeks because they said I wasn’t willing to help myself when I was trying my best. I get that it’s in the past but I still traumatises me..
Why can’t I stop thinking about it?
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