Second period after birth

After I had my baby two months ago I had my first period for like 2 weeks and it was really heavy. Just recently got my second period. I think I've been on it for almost two weeks at first something came out...it didn't look like a copy. I don't know if it was part of my placenta or what but it doesn't seem like I'm even on my period. It's very very light...Like not really even spotting. I'm on DEPO. I don't know what that was at the beginning of my period it kinda worries me...It doesn't seem like anything is wrong but last night I had really bad cramps... what do you guys think ???