Nasty smell after sex

So sometimes not every time but after sex there is a nasty smell sometimes fishy sometimes not. I donthave any infections I have been tested. Is it possible my bfs penis could be causing it because sometimes when I give him head before sex he smells fishy but it could also be me because after he fingers me his fingers smell abit fishy but I thought that’s normal. Anyway I can literally smell like a horrid smell throughout the room he has never mentioned it but if I can smell it he must be able to aswell