I Got Off My Period A Week Ago, Then It

I got off my period a week ago, then it started back up yesterday. Last week it lasted my normal 3-4 days and the bleeding was normal. But then it started back up yesterday and since then I have been having stomach pains and headaches. The bleeding is heavier then usual. I don't know what caused it. I am on the pill but I take it daily and at the same time. So, I am really worried. Can you possibly help me figure out what's wrong?