What is it!?

So last night me and my husband had sex. Usually right after, I go and wash off, pee, ect. But last night I was soooo tired and I just fell right asleep. This morning I woke up and my underwear was soaked and I had this horrible smell coming from down there. It is truly disgusting. I showered but can still smell it a little. Has anyone ever experienced this? Could it be that my pH was thrown off balance!? I feel so self conscious.