I'm sorry to hear about all of your problems and hope you get some answers real soon

!!
I agree with what the others have already said, ask if you could have a pillow to put under your stomach as that may help you and ease some of your pain. I'm not sure how they do blocks exactly as I was put to sleep for mine as i'm a child but have you asked about an epidural if you can stand injections being put in your back? I believe for those, you have to bend forwards so that might be easier for you as most of the time, you don't have to lay down. I'm not sure what type of back issues you suffer from so not sure if that would be beneficial but it might be helpful. Also, ask if it is possible for your doctor to sedate you - I know it sounds really scary but that might help with some of your back issues and it might actually be better for yourself as you shouldn't feel any pain during the procedure.
I hope you get some answers soon and I am thinking about you. Please keep us all updated when you can!