What Causes Painful Periods With Chocolate Cysts In Ovaries?

I got married in 1999 in july n conceived normaly in august same year.i was 23yrs.Then later i started getting painful periods n was unable 2 conceive n in 2005 went ultrasound scan n report was anemia,bulky uterus,chocolate cysts for which laproscopy was done n i conceived in 2006 n got my baby prematuredly delivered in 7th month in march 2007 due 2 high B.P. n again same painful periods with clots n same repeating of cysts when ultrasound done.Please help