What Causes Irregular Periods Along With Brown Vaginal Discharge?

I have had really different periods the last few months. I’m 30 years old and have always been very regular. I’m now getting a lot of brown discharge for days before and days after my period. I’m getting my period 2 weeks early twice in last 6 months.. something is not right. In the last week, I’m felt something not right down below, like a dull ache mainly when I go to oed, like pressure but sometimes feel it when I move a certain way but mainly on my left side