If his head is facing down towards the ground, it could well mean he is feeling very ill. My cat did that when he had cardio issues. You should probably take your elderly gentleman to the vet.
Hello~Maybe kitty is trying to get rid of a hairball, does he sound like he wants to vomit at times when like this. I know when I had my kitties, they got in this position before throwing up the fur ball. Taking him to the vet is a good idea, especially if this continues and he isn't getting rid a fur balls.
I hope he feels better soon.
The vet wasn't much help. She said you have to expect an older cat to have problems. He is shedding like crazy, also. I brush and brush and still his fur is almost falling out in clumps. I don't think it's mange. He is an indoor cat only and not exposed to many things. I just wonder if the shedding could be due to it's been so unseasonably hot lately. I don't have air conditioning and where the cat stays most of the time, it got near 80 F for several days.