Constant sour taste in mouth

My mother who is 65 years old has been complaining about constantly having a
real bad sour taste in her mouth.  She brushes regularly and takes good care of her teeth.
She can not get the true taste of anything she eats because of the sour taste in her mouth.  She also
has gotten to where she has to get up in the middle of the night to rinse out her mouth because the taste
is so bad and seems to be getting worse. This has been going on for several months but keeps getting worse.
She has seeked medical attention and she has only been told that when she had surgery on one of her ear drums that the doctor who preformed the surgery could of damaged a nerve that is associcated with her taste buds. Does
anyone know what we can do or what type of medical doctor we should see.

[scottma]

Seeing a neurologist or orofacial pain specialist is advised.