What Is The Treatment For Heavy Bleeding And Cramps?

I had very light spotting for 3 days and then had light bleeding for 4 days the second day of light bleeding went to Gp felt very ill and blood pressure was 60/80 very low she then gave me some meds for sinus and told me to take it slow , one week later i got bad cramps and then started to have a heavy period as in today i had to change my sanitary pad every 2 hours, what could this be?