Brown discharge 2 days before my inactive week, but ive been on birth control for while. should i take a pregnancy test?

It would reassure you.

This sort of "breakthrough bleeding" is not that unusual and is only very rarely associated with a pregnancy, especially if you have not missed or been late with any pills, have not taken other medications (particularly antibiotics) which might interfere with them, and have no other symptoms. If you wish you can do a pregnancy test before starting your next pack.