Hi, I am a 21 year old female, and I went to the ER a couple weeks ago because of a missed period and pelvic discomfort. I was given a pelvic exam, and I was diagnosed with PID. However, I didn't have an STD. I have a faithful boyfriend of 2 years, and neither of us have any STDs. Still, we wear a condom every time we have sex. The nurse told me that sometimes normal bacteria that inhabit the vagina can travel up through the cervix, infecting the upper organs. I understand that PID is a serious condition, but I don't understand why it happened to me. I also read that once you have PID once, you're more likely to get it again. I'm really scared of getting it again, so I wanted to know how I can prevent it considering it wasn't caused by an STD. What could explain why I got it, and how can I ensure I don't get it again? Please let me know. Thanks.