Question (first timer here)

Hello, currently 19 weeks pregnant with my first child. I started to experience brown discharge (brown po, hindi red, hindi pink) simula nung mga 17 weeks. I had a very stable and uneventful first tri, but ngayong second tri biglang may ganto. Nagpacheck po ako sa OB twice na since experiencing this but all exams normal including u/s. But still may discharge on some days (mga once or twice a week). Should I be alarmed? Thanks po.