My Dad Is 80 Yrs Old And Has Parkinson's. Just

My dad is 80 yrs old and has Parkinson's. Just this past week, he's lost his appetite, says nothing tastes good and barely drinks much all day. I'm concerned he's getting dehydrated but also concerned about what is causing these issues. I was hoping it was a short term thing but it's continues. He's difficult to get out to get to a drs apt, physically and just being stubborn.