I hope anybody know the answer for this one.

We've been together for 8 years. Ok, after my man and I had sex...he tells me that he feels itch on his penis. He thinks that I have yeast infection, but....I already saw ob-gyn, did vaginal swab to see if I have any kind of infection and results are negative, there's none. I don't know why its causing to itch? I'm just puzzled. %-) We never had this problem til now.