Sudden pain in both legs plus sciatica in right leg

I’m 84years old and have multiple health issues-lower back pain,neuropathy in both feet, pulmonary hypertension, etc. I had Polymyalgia Rheumatica for 13 years on a steady diet of steroids & methotrexate. Also a mastectomy & lumpectomy. Recently, I have begun to have pain & weakness in both legs plus sciatica in my right leg-making it impossible to sleep well. Also,extreme pain in my lumbar & both hips. My balance is way off & I “almost fall” off & on during the day. Walking is painful and exhausting. I recently went to the Good Feet Store & was fitted with orthotics to even my leg length discrepancy. Could that cause all this pain?