Hey Trisha,
Sounds to me like he might have gotten a bit much of 'a good thing' with the grazing and all. I'd try giving some probiotics (if he will eat any amount of grain I'd try putting some yogurt culture *powder* on it) along with some molasses and apple cider vinegar. If he won't take that, then you might just want to put together that 'chute' and force it down him. Also try offering just a grass hay and see what he does with it. It really sounds more like an upset rumen than anything else, but I'm only a novice with calves myself.

How has it gone so far for you? I noticed it's been a few days.
Rena