Our baby nubian is sick?

He is a couple weeks old and starting to eat weeds and grass. We bottle fed him for a while and slowly weaned him. Today I saw his lips have bubbly green goo with a little bit of grass on them and he is staggering around. His belly is empty and he barely moves can anybody help me figure out what is wrong. I saw another website where a goat had the same symptoms plus he had pink eyes which our goat doesn't have. He looks right now like he is chewing cud but his belly is so empty I wouldn't expect him to have anything to chew. Can anyone tell me whats wrong with him