2 Periods back to back....

Nessa
Ok so my period started for the second time this last Sunday (12/6/15). But I had JUST ended my last period about 3-4 days before that...both times at about a medium flow. Has anyone else gone through this?? Also I had my first depo shot in June. Is it possible the shot is really messing up my cycle?? I only took the one shot so I wouldn't have a period in my wedding day & haven't had another shot, pill, or anything since then.