I am sorry if this might gross out some, but when you have intercourse, you and his body fluids mix and if he climaxes inside you, without a condom ,it takes a while for that to exit you. I have always noticed this, I just wear a pantiliner the day after, and by then your vagina naturally cleans itself. It also helps if you can urinate after sex to get most of it out. It is also good that it prevents urinary track infections. Hope that helps, but unless the smell is really bad, then it sounds normal to me.