What Causes Pink And Brown Vaginal Discharge After Menstrual Cycle?

I had a miscarriage 3 months ago. I got my period 43 days after and it was a completely normal period. 30 days after that period I started getting spotting (I thought this was my period starting) but it continued and has been for the last month almost. It's been pink, red and brown. But never heavy enough to be a regular period. It's been brown for quite a few days (sometimes even beige in colour). This has been occurring for almost 4 weeks straight. It's on and off again but never stops for a full day. What could possibly be wrong with me?