Fishy Odor after sex while TTC for 2yrs. Someone please help.

I have been TTC for 2yrs now and the fishy odor returns EVERY MONTH. EVEN AFTER ANTIBIOTICS. EVEN AFTER A CLEARED PAPSMEAR. I give up on my doctors they say all tests say I am fine. I need advice and help I am loosing my mind. We conceived our first baby on 6months and we didnt have these issues.