What is going on with my body? Recently off depo shot?

I've been on deprovera for about 6- 61/2 years. (I realize the recommendation is 2 years, but whatever). I have been off the depo shot for about 2 months now. I still haven't gotten a period, I have gained about 25lbs and just recently my nipples have become extremely sore and I've been having back stomach aches. I've also noticed that there are stains in my bra (where my nipples go). It that just sweat, or what? Never had that happen before. I've been to the gym off and on, and have had a really hard time loosing anything. Seems like I will loose a few pounds and put it right back on. I have never been this heavy. My normal weight was about 125ish. I KNOW for a fact that I am NOT pregnant, so what in the world could it be? I haven't really changed eating habits or anything. Im a 22 year old female. I realize this isn't much to go off of, but will coming off the shot cause me to be in this much pain and to GAIN that much? Seems like everything started after I got off. When I was on, I NEVER had a period, and I was 125lb-130lbs when on it. I'm about 5'2. It's insane, its driving me absolutely crazy. I feel terrible and I don't want to waste my money going to a doctor. I've been to the doctor with stomach issues before and they put me some some medication that helped, and then I came off of it. Any guesses as to what it would be?