Lupron Flat on My Back, Fibroid, Lower Back Pain, Hysterectomy, 28 Days

I'm 49, still having periods every 28 days. Have been doing the "watchful /waiting" thing with my doctor for 4 years with a fibroid. This past year- fibroid more than doubled in size (now at 16 weeks size uterus) , the tumor is sitting on my bladder and causing problems in that area. Monthly bleeding is getting awful and pain worse. Doctor says it's time for hysterectomy because I'm no where near menopause for this thing to shrink to the point of stopping my problems and the problems will only get worse as this "thing" continues to grow.
I'm on day 17 of my first of 2 Lupron shots to prepare me for Laproscopic Hysterectomy. So far I've had headaches and spotting that are bearable. My scary and painful issue is BACK PAIN. It first started on day 3- lower back pain that felt like my spine was being squeezed, pressure in my uterus, neck and head. I felt like I was going to have a stroke. Called doctor- she said it was a side-effect and should get better. Lasted 4 days. Now- it's back!!!! For 2 days- can barely walk and the only way to relieve pain is to lay flat on my back on a hard surface. Can't take ibuprofen etc. because of allergies so I'm stuck because Tylenol does nothing.
Anyone else have this issue?
I'm considering not doing the 2nd shot. Surgery is scheduled for end of July and I don't think I can spend my summer like this.