behavior of my bearded dragon

Question
Hello my name is Morgan and I have had my bearded dragon for about 6 years now and when I bought her from the pet store I was told she was around 2 years old.  Around 1 year ago I changed her diet and added adult bearded dragon food and recently she has stopped moving and just sits on the coldest corner of her cage (55 gallon long tank) she has a medium size water bowl that I fill and clean every other day and I still regularly give her her food but it has been almost a month that she hasn't eaten and I have tried to move her into her heat light and she just moves back to the coldest side of the cage.  I am so worried that she is getting older and is dyeing.  My boyfriend used to raise and breed other kinds of lizards and he says that her lack of movement is not healthy.  The cage has calcium sand in the bottom of it and she has two logs for basking at different levels of her cage.  I just don't know why this is happening and I am really worried.  Please help.

Thank You,
Morgan

Answer
This is not a good sign, this could be due to the fact that she does not like her diet, if she is not eating it at all. The worst case that could be happening is the aging and dying of her, hopefully this is not happening. Your boyfriend is right, it is not healthy for her to sit in that cold spot. she must be taken to a vet, no one not even an expert of my expertise can diagnose what she has.