What Causes Brown Vaginal Discharge And Cramping While On Ortho Tri-cyclen?

Hi. I ve been on Ortho Tri-Cyclen birth control for about 3 months now and I ve been experiencing brown discharge and small cramps. the cramps just started yesterday but the discharge has been going on for almost a month. I ve only skipped my period twice while being on the pill. last period i had was early January and i had sex on Friday. I m slightly worried I m pregnant but have done research and most people who have had the same thing say its from the pills. I m not sure though and i need real advice i can trust. anything helpful and reassuring would be greatly appreciated. Thank you.