What Causes Heavy And Prolonged Menstruation?

Hi--I have experienced heavy menstrual periods in the past and my doctor who is no longer w/ the practice recommended a combination of Sudafed, Ibuprofen, and Vitamin C every 4-6 hours during heavy days. However, I cannot recall the exact amounts of each...can you please advise? I am 34 y.o., 5'6", and currently 175 lbs. w/ a hx of fibroids (but had these removed about 3 years ago).

Thanks, Jeanna