As for him not laying down, that's the instinctive drive to not look like the weakest target to predators. It's just built into them, so to speak, to not let on at all that they don't feel good.
And getting the mash in him twice a day is good, but I would love to hear that he tried to eat in his own.
Try scrambling some eggs, add mashed up garlic and some crushed cayenne, and offer it to him. Garlic powder is an acceptable alternative, but NOT garlic salt, and the cayenne can also be powdered. Try to see if he'll give it a try. If he won't eat it, you can give it to some of your other featherbabies, LOL! (I figure that if its an illness, they're already exposed, so it'll do them good).