How To Cure Severe Pelvic And Abdominal Pain Post Vaginal Hysterectomy?

I had a vaginal hysterectomy 6 weeks ago. I had sex 3 days ago and ended up in the Emergency Room due to severe pelvic and abdominal pain. I was told that my vaginal cuff was intact but I had a small amount of free air in my abdomen. Today I saw my GYN and was told that it looks like I have a cuff abscess and possible fluid collection. I was started on oral antibiotics and may have to be re-admitted for a cuff I&D if the oral antibiotics don t help. Why would this happen after 6 weeks.