😷smelly!!

Why does period smell. 
I have been on mine for a month , and it stinks! My kinda bf(lol) and I wanna have sex, but I just tell him I'm cramping ,and my flow is heavy. Truth is I don't want him to be like wtf is that smell?? Lol
He said he's never had sex with a women on her period so he was unsure any way. But still any ideas why it's so smelly:/ 
I'm so embarrassed I don't ever leave my house.