Could i have an infection or what?

Since around April, i have been having this constant pain on the right side of my belly. I went to the doctor and she said she wasn't sure but gave me an antibiotic and pain reliever, it seemed to have helped but now i am still having the pain on and off. It also seems to be worse around the time my period should come. Last ual activity around June 3. I also had my period back to back for about three weeks in March to April and then this pain.The doctor kept askin if i was pregnant but i told her no, i did suspect pregnancy in March but then the 3 periods, Can someone help me out please. I am planning to go back to the doc soon but just want to know if anyone has any experience like mine