Hi. Thanks for your query. Pinched nerve is a nerve which has been pressed, entrapped or kinked by anything in its normal course by whatever disease. In case of your Mother the fall on the back must have caused the the muscles go into spasm that can cause pinched nerve syndrome due to entrapment into the tight muscles or can be due to inflammation of the vertebral joints. I would advise her the following: MRI of the back with a pointer at the most painful area so that the study can tell us the exact diagnosis. and get a plan of treatment. Since she is alright with present medication for thyroid , continue the same treatment as before. Get an opinion of an Orthopedic surgeon for backache.