pms or pcos?

questions.... about a week ago I had really bad cramping from my right ovary, today I get a crime scene period. last month I had cramping from my left ovary, no period... month before cramping from my right ovary and no period. how can I tell if my ovary cramps are period related or a cyst bursting? I have been diagnosed with pcos, I take metformin, and I usually only get a period 3 or 4 times a year