I have a question in regards to antibiotics and birth control. I was prescribed amoxicillin for an ear infection. I know it can cause birth control to be less effective. But after seven days out if the ten I had to take the antibiotics, I started having breakthrough bleeding. I am definitely not pregnant and I haven't done any sexual activity for over a month. I also have not experienced this at all since I've started taking this specific pill since March. Could it be happening since amoxicillin decreases the effectiveness of the pill? Or is this not normal?