Is it normal that i might have an infection doctors don't know about?

OK so my vagina is always a bit itchy,
i have trouble peeing if it's not urgent, i smell fishy after sex, i cant masturbate multiple times in a row like i used to, intercourse is always painful BUT i've been to SEVERAL doctors already and NONE of them were able to figure it out
I went for bacterial tests, yeast, stds etc AND ALL OF THEM CAME BACK NEGATIVE??
(this happened right after skinny dipping, not sex so i doubt it's an std)