Talk to Neuro Physician on Severe Backache

My mother is suffering from backache from the last 15 years almost and it used to come and go on and off we. Have done mri which came out normal and x ray which showd mild disc compression in the last two vertebrae the doc gave some pain killers and recommended physiotherapy Now recently it been 2 weeks almost my mom is in severe pain she gets fever due to severe pain please tell me what could be the reason of backache with fever and who should I consult