Suggest Cure For Painful Periods Which Is Dark In Color And Sometimes Clots

Hello. My name is Leighann and I am 43 yrs old and a mother of 3 girls. I started my period at the age of 15 and since then I have two periods a month. I usually have a period at the first week of the month. It averages about 7 to 8 days and then 3 or 4 days later, I will have another period. They are very heavy,painful, dark in color (dark red) and sometimes in comes in clots. I have tried birth control pills in the past,but nothng helps. Doctors have told me that it will get better after having kids,but it has gotten worse. When I am on my period,I can't function. I am usually in bed or in the bathroom due to nausea and vomiting. Please help. Thank you