Thanks everyone for your good wishes, thoughts and prayers for him, he's still gagging occasionally, would not eat the 1 tbsp of beef or 1 tbsp liver this morning and is still having diarrhea, though it is partially formed and a normal brown colour instead of the light brown liquid of 2 days ago.
I just offered him fresh water with pedialyte 50:50 and since he saw me putting the pedialyte in it, he won't drink. I'm hoping he gets thirsty enough to take a drink. He seems suspicious of everything I put down for him (food etc) since he started barfing up his food. Not sure if it smells odd to him or what, but he doesn't seem to want to touch it.
I'm going to wait a few hours and see what happens before doing anything. The mobile vet told me yesterday he would have to be hospitalized today if no better. He definitely is more alert today than he was and is doing normal things like blocking the cats from getting into the kitchen to their food and barking at them if they attempt to jump him, calling my son from downstairs by barking for him, and moving around the house. He slept in the living room last night where he rarely sleeps.
Just keeping my fingers crossed still and can't figure out what is causing this continued illness other than the tumour has invaded areas that won't respond to any treatment.