Hey i hope you've been having a nice day, i'm sorry you've been feeling kinda off lately
exams are a huge stress and can trigger episodes of mental health crises in some people, especially with a pre existing mental health illness or psychotic episode.
i am in no way a mental health professional, but i do have two serious long term mental health problems.
what i would say is that you are having some form of panic attacks every so often, and the intrusive thoughts often come with these, i'm not sure why they are sexual though. it is different for everyone.
major signs to watch out for are any delusions or really weird thoughts and hallucinations or hearing voices.
or feeling really cut off from reality/spaced out and wanting to hurt yourself or anyone else -if so seek immediate help.
you should try and get some support from a mental health professional so they can guide and monitor your symptoms incase they develop.
make sure you don't forget to take any medication you might be on. take regular breaks from revision and make sure to get some fresh air, regular sleep and eat properly. severe sleep deprivation can cause psychosis.
i would say try not to stress about exams, but it is inevitable. i'm doing mine too at the minute and i have to be extra careful.
i hope you found some help in my advice
x. PM me if you need anything.