I Have Four 'symptoms' That I've Had Progressively For Several

I have four 'symptoms' that I've had progressively for several months.
1. an oily or greasy sensation on the roof of my mouth when eating...or drinking, especially milk or other dairy products.
2. a mild burning or tingling of my lips as well as dryness, especially at the corners of my mouth.
3. a sensitivity of my tongue.
4. a diminishment of taste.
Is it likely that all of these issues are related, and what can be done about it? I am a 76 year old male, and in generally good health.