How do I get rid of this heavy anxiety feeling?

This feeling makes me want to sleep all day, I am not motivated at school, and am not able to get to the gym. What happens is I will kiss a girl or be ual and then after the incident it causes me to need to get tested for STDs, and up until 3 months later and I get tested something lifts from my chest and I am normal again. I have repeated this three times in the past year and my doctor thinks I am nuts. I tried to call over the phone for him to send my lab paperwork but he is persistant that I come in for it and then get it done. Good thinkg for insurance beause my mind is not cleared until I get tested. Ever since I hooked up with a hooker in the Islands I have never been the same. If I had a minor abrrion in my mouth a week ago that is cleared, and I kissed someone then I would need to get tested. I am weary of kissing my family members of the worry of getting or something. I have seen shrinks etc, medicine etcc and nothings working. DO you have any advice or have you experienced this before. Its all I can think about.