My periods have always been very regular, aside from once when I had a chemical pregnancy. This is my second period in the last three weeks, and I'm bleeding way more than usual. I normally have a heavy flow for four days and a medium to light flow for another three or four. This time it's very very heavy, and it's not showing any signs of slowing down. I'm starting to become very weak and very dizzy if I stand for long periods of time. I'm going to Planned Parenthood on Monday to see if they can help, but it's all I can afford. What could be wrong with me?