Everytime my man cums in me I get an infection

Tenchinally I don’t know if it’s an infection everytime but it has turned into one before. I pee right after and clean as best I can but then I slowly start to get an odor and then it becomes out of control with in a few days. It’s been better in the past few months but today it’s really annoying me and before in the past it’s been so bad that I’ve gone to doctors or was able to smell myself through my clothes. It’s not a big deal if he has to stop I just want to know if this is normal? Is it possibly his cum throwing my ph balance off? It’s frustrating because we’re trying to get pregnant but it makes me not even want t have sex.