Okay.. So I'm really confused.

I started taking a birth control last Thursday, And I stopped 3 days ago because it was making me really sick. My last period ended on Wednesday, before I started taking it. I had a brown discharge and I knew it was normal, I had already gotten freaked out the first time it happened, But it's happening again now and I'm having really really bad cramps to go with it. I was just wondering if it could have something to do with the birth control I was taking or if it was normal.