Why am i having breakthrough bleeding and stomach pain while i'm taking birth control pills. the breakthrough bleeding lasted about 4 days and stopped. i k ow i took a pill a day. could it be pregnanc?

Breakthrough bleed: Breakthrough bleeding (bleeding at the wrong time) is very common on birth control. It happens in about 1/3 of users. Its no big deal and usually self corrects over time. If you are not satisfied or it continues to happen then consider using a different birth control method. It is a common side effect and does not mean something is wrong or that the pill is not working. Take a test if concerned