Breakthrough bleeding?

I just started my BC (Junel FE) in March and everything went well. When it came time for my period, it came and went as normal. But when I started my second cycle of pills, on my second week I am experiencing breakthrough bleeding. Its mostly brown with a little blood. Its been going on for 3 days. Is this normal? Its really starting to worry me. Also, I have read that higher levels of estrogen can help stop breakthrough bleeding but I that's why I'm on Junel FE in the first place. I can't have a high amount of estrogen. Is there any other way to prevent this? Thank you.