Good Morning Curious,
Welcome to our message boards.
No. You're not overreacting. It sounds like you want to know what's causing your symptoms. That's completely normal.
There are any number of things that could be causing you those symptoms but the 4 negative herpes tests are pretty indicative that it's
not herpes. Were those antibody tests?
You didn't mention whether or not you were using condoms. If so, have you thought about it being an allergic reaction to the latex? It could also just be irritation simply from the friction of sex.
If you're not getting any relief, there's nothing wrong with calling your doctor and asking more questions. If you're not getting anywhere, it might be worth checking with another doctor about why you're experiencing your symptoms.
I hope this helps,
Dharma