Pain, STD, UTI

Soo I’ve been dealing with painful (what feels like) cramping lately. I have an IUD and I had gone to my OB doctor to check to see if the IUD was still in place since I was having extremely painful cramping, to the point it brought tears to my eyes and wouldn’t allow me to walk. They did an ultrasound and everything was fine. No ectopic pregnancy, no cyst, IUD in place. They swabbed my cervix and did a urine culture. A week later, they called me to tell me I have Chlamydia and a UTI. They immediately sent over a prescription for a gram of Azithromycin (to treat the Chlamydia) and Ceftin for the UTI. I took the gram of Azithromycin that day, and started the 10 day antibiotics of Ceftin that I just finished taking the other day. Today I have experienced close to the same pain I was feeling before I discovered I had Chlamydia. What else could it be? I go back in a couple of weeks to test again for Chlamydia to ensure the antibiotics worked. Has anyone else experienced anything similar? If so, what did the doctor tell you?