Casey had this problem once from meds, she was vomitiing also. Its good he isn't vomiting. The vet had me give her ice cubes to lick, I would hold it in my hand and let her lick it so she didn't get dehydrated. I called in sick to work for 2 days with that, scared me to death. And actually I put her on a boiled chicken and rice diet for the duration of her illness and it helped her get better.