Bad pain in stomach.

I've been getting the depo shot. My last appointment was scheduled for Aug. 24th I wasn't able to go because my medical is not active and I'm still trying to get new medical. I have not had my period since i started the shot. Me and my husband do it alot without a condom and I'm having really bad stomach pains kinda like cramps but a Lil worse and I'm starting to feel nausea coming on. I also havnt ate anything today because when I tried I felt sick to my stomach.. I'm very stressed out as well and have been sleeping on the floor; So can anybody tell me what's wrong. I know its alot of information but I'm trying to avoid having to go to the E.R .