Please help.... what is this ???? (Explicit & Gross)

Ive been on the depot shot for about a month now and I drink heavily every weekend. My boyfriend and I used to have sex every time we’d see eachother. (We’ve separated but not the point). Anyways, I was taking a bath after work, and THIS came out of me. It’s huge and slimey and has veins running through it. I didn’t have to pull it out or anything, it just slipped out into the water! I felt it, looked down and at first I didn’t worry too much. Then I pulled it out. It’s about 4 inches. I had been cramping all day before it happened, but not like regular cramps, seriously painful agonizing cramps, making me fall to the ground. Since I pulled the thing out of the water to take a closer look at what I ‘birthed’, my cramps have faded away. Any clue what THIS is?