His diet has not changed. He is given Kaytee supreme parrot food. In addition he is given fresh vegetables like apples, oranges. This is the same diet he has been on for years.
To clarify about the sleeping. In the past he has only slept (hidden his head in his feathers) at night when his cage is covered. For the last few weeks he is sleeping during the day quite often. He also makes the 'snoring' sound occasionally when he is awake also. He has been having these symptoms for about 3 weeks now.