My Grandfather Is Suffering From A Bitter Taste In His

my grandfather is suffering from a bitter taste in his mouth and everything he eats tastes "like garbage" and gags him. He was recently diagnosed with Parathyroid issues and I was wondering if this could be effecting his taste. He hasn't had any tests done yet and doesn't meet with his doctor for another 5days. Having these issues he's lost almost 25lbs in 2 weeks from not eating--or barely eating. And I believe that he's also become depressed. He refuses to go outside and be active....even though he was VERY active up until about a month ago when his arthritis pain got him down. I'm just trying to make him realize that the food doesn't taste bad because it's BAD---it's something to do w/ his taste. Any advice would help!