Why does my vagina smell of semen?

I am 37 weeks pregnant and my vagina smells horrible! It smells so strong of sex.. like semen!!! Thing is i've had NO sex at all for around 8 weeks atleast. I had a urine test and a swab done, no infections. It's milky white discharge that turns yellowish on my undies and smells so awful i can't stand myself... even my boyfriend says i smell :(