What Causes Heavy Vaginal Bleeding?

I just found out that my husband has been cheating on me and I have been on the depo shot for almost 7 years.....I have just passed a blood clout I have cramping just today and I have some bleeding. Is everything okay with me. He says they used protection but I worry of why I'm bleeding all of a sudden. I haven't been eating well and drinking more than normal to go to sleep. Should I be worried