I'm no the expert here, but I would suggest if he's having trouble swallowing you may want to look into some frozen brine shrimp. They seem to be able to slurp those a lot easier than they can CHOMP, CHOMP pellets.
Just be sure not to put too much in there. It's so easy to overfeed brine shrimp, and so easy to sully up the water. I suggest thawing it in some of his tank water, then sucking up one brine shrimp at a time with a dropper. Squirt slowly or it will shoot right past him.
He needs calories to rebuild fins, immune system, etc.
Best of luck!