Good news everyone!
He seems to be improving!
I had just finished putting his lid back on after doing a water change and peered inside to look him over. To my dismay, he was nowhere in the tank! Somehow I couldn't locate him in the small 1 gallon with no gravel and one decoration. I frantically checked the area around the tank to see if he had jumped out, but he wasn't around.
I peer back into the tank to try to explain how he could have vanished and what do I see peeking up at me?
He had backing himself into a small cave in the decoration, which was not its intended purpose but he must have wanted a cave. Silly Betta!
Peeking out more to see why I was freaking out.
His improvement thus far has been that he's been a little more active in the tank and staying less vertical. I still haven't seen any poop, but I managed to interest him in a NLS pellet!