Hi. My 74 Year Old Mother Has Been Practically Bed

Hi. my 74 year old mother has been practically bed ridden for almost 2 months now. We have gone from one dr to another trying to figure out what the problem is. it started in her back and has moved to her uper right thigh. She can not walk or stand for any length of time. Her leg is hot. At night the sheets touching her leg hurts. She is on several different kinds of pain killers. None of which help 75% of the time. We saw her back surgeon today and he said she should see a neurologist. do you have any ideal what this could possibly be? We will have to wait 2-3 weeks to see a neurologist and being that she has been going thru this for 2 months now does not make us happy.