After a series of tests, the doctors could not determine what was wrong. They put him on an IV for the day to help him regain his fluids.
When I picked him up he seemed to have more energy, but still seemed a little sicky... so I got him a new bed to make him more comfortable :)
As strange as it sounds, Dr. Rao prescribed 2.5 mg of Pepcid AC for stomach acid, and Pedialyte to help restore his electrolytes. She also put Max back on the percription food.

Much to my surprise, Max enjoyed the orange-flavored Pedialyte and even ate his new food. He seems to be feeling a lot better, but still is not 100% back to normal.

Hopefully he'll be back to chasing squirrels again soon!