I honestly have no idea. It could be bloat.

When you pick him up, does he feel odd? Has he always been bloated and if not, when did it start? Did something substantial happen recently that has caused him to bloat up?

I would try to retrace my steps, to see if anything has changed.

For now, maybe it's best to take him from his home and put him in a substitute enclosure, like a big plastic container, and see if he eats then. I can't imagine he's gassy because he isn't eating... but it could be a possibility.

Or even get a glass bowl and drop his crickets or other insect food in there and see if he eats them. They won't be able to escape once in the glass bowl[most insects anyway] and you can monitor how much he eats, if any.

I'm not very experienced with these frogs, so I'm not sure.

Hopefully someone more knowledgable will come along.