I also go to pain mangement for my Lupus, Sjogrens, and Fibro pain and also the pain in my lower back. I have also had 2 injections, one of them being a Facett injection and niether one worked. Do you use a TENS unit. This helps, I also use a heating pad and narcotic pain medication. Last time I was at the pain doctors they said that if the last 2 injections didn't help, then chances are more would not work and they would not recommend anymore. I also use a cane to relieve some of the pain and take some of the weight bearing off. These are just some of the things I have to do to get relief because the injections didn't work for me, I hope you can find some relief
I have had multiple corticosteroid injections in my neck as well as my Sacroiiliac joint. I had only 2 in my SI joint because it was doing nothing for me but I have had 6 in my neck over the course of 2 years which were remarkable. Sometimes these shots help and other times, not so much. It's all depends on how one is going to respond to them. If I was in your shoes, I would call the doctor to see if this is normal and go ahead with the other injection. If after two injections you don't get any relief, then it may be that these shots aren't going to work for you. Did you ice your back after the injection?