I Had Some Pelvic Pain In The Middle Of December

I had some pelvic pain in the middle of December and had an episode where I came close to fainting. As a result, I went to a clinic. I was diagnosed and received treatment for a bladder infection. I did not have symptoms of frequent urination. The medication may have helped the pain but about a week later, I had some slight vaginal bleeding and the pain was gone. I am now experiencing the discomfort again. I have an IUD but have not had intercourse for four years. Could I have been misdiagnosed? If so, what else could this be?