Cramping really bad

I've been on depo for 4 years. Well here lately I've noticed that I cramp at least every other day for past month. I woke up this morning about 430am with my cramps hurting so bad I couldn't sleep. The thing is I NEVER start my period. Idk if this is a side effect of the shot or if something is going on. Anyone that's been on it did you have this problem!? Thanks ladies