Sex and smells

Okay so my SO and I haven't been able to have sex much recently because he's in the military and is away. Well he's home right now and I've noticed again that every time we do anything I start to smell. I checked to make sure everything was okay before we did anything  and it was okay. Then when we went to bed and he started fingering me I smelled different then after sexy I smell an acid fishy smell. How do I fix this