we have a calf that lost its mother about 2 weeks ago. It appeared to be doing fine by "robbing" off a few other cows----we left for a stockshow for a week and the person checking cattle didn't notice the calf. Now the calf is scouring, and it appears to have tried to survive off of eating grass. The calf's mouth and surrounding muzzle are very dirty and colored a greenish color--it seems to almost be regurgitating what it had eaten. What is going on, besides dehydration and starvation? Could he possibly have a disease? I fed him milk replacer and he seems to be doing a little better.