My grandma has burning sensation in her body, but freezing on outside?

My Grandma, age 75, has been experiencing a burning sensation inside her body, but is cold on the outside, for about 6 months. There is no pain involved or anything, it is just very unpleasant for her to feel hot on the inside all the time. The docters tell her its hormones or something and act like she's crazy. They tell her it could be anything but never have any conclusive answers. This is very frusterating for my Grandma. Please can anyone help her. It would be much appreciated.