What Causes Blood Clot Menstrual Discharge And Stomach Cramps?

Hi for the last 4 days i have had a abnormal period lots of bright red chunks, i also have severe stomach pains sorta like contraction like symptoms. It was so bad I had to go to the emergency room. The blood work showed i wasn't pregnant but i have very low c02 in my blood as well as deydrated and lack of electrolytes. I will be seeing my doctor 2morrow for further check up. but was wondering what this could be? I have had stomach pains off and on for a couple months after i eat ( sharp pains that go away)