We are kinda in the same boat. I was diagnosed with endometrosis back 2001 after having my first child..I had a cyst that grew along with the baby and when I had it removed that's when they found out. According to the doctor I was not supposed to have kids.. it was way to bad..In the end the doctor said that I had to have my whole left side removed so to have another baby I would need fertility drugs.. I did use fertility drugs but it didn't work and after 25 month I finally was pregnant with my second child.. Now that I have 2, I decided to get an IUD.. and after about 6 or 7 months I had severe back pain that I couldn't get out of bed. Lifting up was unbareable.. I was in the bed for 3 days straight one weekend in September..but it did finally go away.
Now to answer your question.. its hard to say if the endo has anything to do with it.. I didn't realize until weeks later that the back pain is a side effect of the IUD..We both have the same back pain and we both have endo so its a possibility that the endo might make the back pain worse.. I'm almost positive that the IUD is NOT the cause of the endo. Many women have endo that have never had children..I was 22 at the time I found out that I had endo and it was at the worst stage so I had to of had it when I was in high school. Talk to your OB again and demand answers..it might take some time, but you can have another child.. If I could with stage 4 endo and only one tube and ovary..I have faith that you will have another child as well..