Talk to Gynecologist on Monthly Period Cycle.

I am having extremely painful periods from the last few months. The pain is so much that I can't even lift my legs and I can feel all pain till my anus. I start to feel dizzy due to the cramps.i can feel Nausea in those days. The flow is alright. Should I go for a ultrasound? If yes then when before periods or during. We have some history of pcos in our family.