What Causes Intermittent Abdominal Pain And Brown Discharge During Periods?

well i have been having this left side pain by my hip and it comes and goes and now for the last 2 days my nipples have been hurting and they are red and my boobs feel really heavy. i have my period last month but it was a really weird one with a lot of brown stuff in it and i got done with it last month on the 26th. so i know its not from my period coming or anything. what do you think is happening?