Has this happend to anyone

My period is 10 days from now been the same time the last 3 months but the last 3 days I've been cramping even during ovation feels like a sharp pain or gas bubble then creates lower back pain same thing happend before my period last month and then I got my period but thought it was a cyst and had a ultra sound they found nothing to be out of the ordinary ...hoping it's not pregnancy as I've had no other symptoms besides this painful cramping