His weight is really dropping and his feces is
getting hard and dry.

Teresa this is a really big red flag for me!!Hard,dry feces are not
good.
How much water is he drinking??
If he were my horse I'd be really concerned about impaction colic.Not
trying to scare you but....been there,done that and it's not fun.

I'd be wanting to get lots of water into him.
I'd also be interested in how much he is eating by *weight* so that you
have a better idea of actually how much he is ingesting.Not much,only a
bit,hardly anything and other descriptions like that make it hard to
really know what he's getting.....to my mind anyway.Make sense?

Lorna