So.. I never smell down there, but when my boyfriend 'goes' inside me (were on birth control, and were completely monogamous) after I start to smell like fishy beach. The smell lasts a couple days, and then it's back to normal with no odour.
If we use a condom, I never smell.
I shower everyday, but it doesn't seem to help. A couple hours later I start to smell again.
Is it just our.. Gooo... Mixing together? Or should I be going to see a doctor?
well... guys semen lasts in your vagina (there's a little culvert up there that collects it) and gets stinky. It stays up there for a few days (Even if it seems like it all comes out, some of it usually hangs in there) Really, if it's only after sex, and you aren't having any other symptoms like funky colored discharge then it's probably just his semen.
you could try a condom and see if that solves it, to rule out everything else.
Usually discharge is a sign of an infection, I'd suggest you hit up your OBG.
As far as the original poster, the answer is most likely yes, a mixture of your "Goo". The male penis can culture bacteria not native to the insides of your vagina, this can cause something like a light bacterial vaginosis where the normal bacterial level in your vagina elevates, this is where the smell comes in. It goes away when your vagina has settled back to its normal bacterial levels.
A way to combat this is as you said use a condom or both partners bath "well" before intercourse.
I smell fishy every time I have sex with my husband if he cums inside me. I have no infection, I have normal vaginal smell (yes they DO smell like a vagina, deal with it its normal) and its fine but yuck after sex. Things to consider... do you do oral sex because saliva has sugars and enzymes that cause odor, also semen has sugar in it and protein and that can spoil and smell. Sex changes your ph balance and odor is pretty normal after sex. Wash up if you dont like it. As long as theres no pain, discharge etc its just a normal part of sex.