Help please

Okay I'm 21 years old and I have a 9 month old. Last night all of the sudden I started having terrible abdominal pain. Its my left side right by my hip all the way over to my belly button. I just got off my period last week which was 4 days late and only lasted 3 days. This pain has me using a heating pad and soaking in a warm tub. Which I never do.

I've never had this happen before. Has anyone else? Does anyone have any ideas what it could be?