I Am A 55-year-old Woman And Have Multiple Medical Problems,

I am a 55-year-old woman and have multiple medical problems, including lupus and Marfan's. I have had my left SI joint pinned. Lately the small of my back, the entire SI/lower back area, has become so painful, I am unable to walk or stand without my pain level shooting up to about 9. I am on a lot of pain meds (through my pain management doctor), and it doesn't even begin to touch the back pain. I have been thinking it was my SI joint(s), but am now wondering if I could possibly have a kidney infection. I have had increasing problems urinating - to the point that, even though my bladder is full, I am unable to void. Unfortunately my primary care physician has had a bad fall and is out until after the first of the year. I am unable to figure out what to do or who to call, or if it's just something I need to get an antibiotic for. Any suggestions? Thanks! Phyllis Schoppenhorst