I have been taking clindamycin for a couple days now and I'm on loestrin birth control and last night I just got a little of brown discharge. This mor?

Breakthrough bleed. Breakthrough bleeding (bleeding at the wrong time) is very normal 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.