And the results are in...
There wasn't a tumor to be found!
This makes me pretty dang relieved to say the least. All that matters now is my boy is at home, happy, and on the mend.
He's on canned i/D right now, and I have my eye out for certain supplements I could use to help prevent situations like this from happening again. (Fish Oil, Vit E, Linoleic and Linolenic acid, a Multivitamin, and/or Vit B injections) We are also going to explore the option of Pancreatic Enzymes if my Vet agrees.