persistent abdominal cramping

Ive been off the pill for 1 month,then just started taking again im a week into them. I had unprotected sex w/ husband. I started as usually had period for like 2-3 days. I took the test and went to the doctor and im not pregnant, but i keep getting these menstral like cramps. I went to doctor again and no prego, but i had a cyst and he said nothing to worry about. He wants to schedule me for a sonogram though b/c of the cramping that i continue to have.. I noticed that the cramping sometimes tends to happen after sex. I was just curious if anyone had advise or had experienced the same thing?