What Causes Heavy Bleeding And Abdominal Cramps After Taking Depo Shot?

Hi so I am currently on birth control (Depo). And for the last two days I ve been bleeding really heavy and having severe cramps. I just woke up not too long ago it s about one in the morning and I could feel that I was leaking . I soaked through an entire super tampon and had blood all over my legs . So I immediately ran to the shower . I squatted out of the shower because my cramps were so bad and all the sudden I passed this huge thick tissue . It was about the size of my palm. It s hard to break up and it s almost like cream colored with some dark spots. I still have severe cramps. Should I be concerned with what I passed?