Hi Judy,
Can not pin down Paul's behavior. But to me, it does not sound normal at all. Even with a clean bill of health from the vet, I would take Paul to another vet. And what I mean is that I would check around your area for a highly recommended AVIARY vet. I would not care how far, I had to travel, I would get Paul there.
I do not want to alarm you. But his behavior to me, does not sound normal at all. I could be wrong, but the only time I have ever heard of a bird leaning or lies down, is when the birdie is seriously ill.
Perhaps I am wrong and for your sake and Paul's, I sincerely hope that I am wrong. And I hope that somebody else has another opinion. Or a solution. BUT!! Once again, if it were me and any of my birds showed this kind of behavior, I would be on my was to a good aviary vet.
My best wishes and good luck to you and Paul.
Kindly let us know what you find out.
Sincerely,
Dave