Birth control & cramping.

So I've always heard that birth control is suppose to relieve cramping but it doesn't do that for me. I've been on ortho tri cyclen lo for about a year now and about every other month or so I get severe cramps to where I cannot even function enough to walk or even put on clothes. Everything makes me feel sick to my stomach. And it only last for about a day of my cycle. I am 18 years old and I have my period every month regularly. What do you think the problem is?