Why Are My Periods Irregular And Painful Post Delivery?

I have been cramping extremely bad. My periods have always been irregular and heavy. 6 months ago I had a cesarien with my first baby. Since my son was born, my periods have been very messed up. One month it will be very heavy, the next month it will be late and very light. Now this month, its kind of like mucus but its a redish orange color. [more orange than red] I cant get into a doctor until next week, so I was wondering if there was any one who might know any possibilities. I was anemic during pregnancy and had unprotected sex only once about a week ago.