Talk to General Physician on Problem In Tongue/taste Buds

Aoa, my mother has got bells palsy 5 months ago. The mouth position is accurate now after physiotherapy. She had ear pain at that time which has reduced by time. But there are still two main problems after that. Her mouth has become very dry after that and also she doesn't feel any taste of food. It seems as if there is some problem with taste buds.From few days it seems as if there is a black spot on her tongue. I am attaching picture. The other problem is that she has a balance problem. She cannot stand without support. kindly guide which specialist we should see for her or what treatment is required?