Fishy smell before/after sex


There is a really weird fishy smell around my vag before and after sex when I have sex in the week or so leading up to my period.

Does this happen to anyone else? It really grosses me out but there isn't any other problems so idk if I should see a doctor.

My partner and I use an IUD so he comes in my vagina- I usually use the bathroom right after and clean myself up but is it possible his semen could be causing this weird smell?

Thanks everyone