M.H.
There are so many different theories on what could be going on but it sounds like you are doing all the right things. You can't force a kid to eat. Be careful with how much of the carnation you are giving him. It would be a filler and he won't be hungry to eat. I use a nutritional drink with my boys but the one I use has all there nutrients they need in one serving. The one I use actually has more nutrtion then 4 cans of pediasure. I can give you more info if you want. Keep offering the foods. The one thing I do with my kids (one of which has sensory processing disorder and gags with a lot of foods)is at every meal I put out peanut butter and bread as an otion at least that way they are getting their protein and it helps them to feel in control. They only choose peanut butter occassional but it is the only option other then what I have prepared.
Good Luck!
~M.