Suggest Treatment For Vaginal Bleeding And Stomach Cramps

I have just had my implant removed 22/03/11 but i was still bleeding so i went to the doctor and he gave me hormone tablets that stopped the bleeding. I stopped taking the tablets monday 11/4/11 and my period started again last night 12/04/11. The bleeding is thin and dark, but seems like pure blood as a lot is coming out when i go to the toilet. It is also causing really bad stomach ache/cramps. what do i do?