Try different brands of birth control. I started on birth control when I was 14 because my periods were so heavy I would get light headed during them and the cramps were painful enough to send me into tears. My obgyn recommended birth control to make them lighter and less painful. I started out on yasmin, and it was horrible! Sure it made my periods lighter but it also made me tired all the time and it increased the amount of migraines I was getting. I went back to my obgyn and she then put me on a very low estrogen pill, because with less estrogen there are less negative side effects. The pill was called loestrin. I had absolutely no side effects at all and felt great and no more cramps! =) I have been on it for 3 years.
So yeah just ask for a low estrogen pill, try out different brands and always use a condom! Even when you are on birth control ;P