What Causes Long Fleshy Kind Of Discharge Without Odour?

I am 44. I have my period for the first time since I had the depo provera shot 1 month ago. Tonight I was changing tampons and I disharged what appeared to be 3-4 in long fleshy substance. It is mostly red (blood) stip like, not a clot. Odorless, veiny. Darker drops of blood throughout. I thought ihad miscarried but don't really think I got pregnant on depo. Besides it's too large and pregnancytestnegative the day I got the depo. I did have cramping the past two days much harsher than ususal. I've read where other women experienced something similar, but no one had any idea what or why. I am quite worried. Can you tell me what's happening?