A Month Ago I Went On The Depo Shot And

A month ago I went on the depo shot and I didn't get my period, and then light spotting started to happen and it got heavier over time and then I woke up this morning and found a piece of meat with blood vessels and the meat was all white and meaty looking and now the spotting has stopped for now but the night before the had some bad cramps and I wanted to know if the meaty blood thing that came out of my was my placenta from a miscarriage or uterus lining or from the depo shot so I want to know what it was