Too much to swallow?

I have a red tailed catfish i bought not too long ago.
Before the flaming starts: Yes, i know how big they get. Yes, i understand nearly every aspect of them, i have spent many many long hours researching them, and i am prepared to take on the responsibility of one.
anyway, i have it in one of my tanks with some otehr fish. i had a feeder goldfish that i put in there. he snacked on part of the first one that was in there, and i thought nothing of it. this was 2 days ago.
today i come home from being out, and i see him, mouth nearly gaping open, and his gills flared. i looked, and it seems he has goldfish in this throat, and he cannot swallow it. Did he just take a bite a bit too big? is this a serious problem? or will it all go down in time?
if this is a problem, is there anything i can do to help?

Edit: here's some pics:





sorry they arent great, im kinda in a hurry... need sleep, and such.

Edit: His stomach seems to be caving in.. it wasnt like this ever before.
i spent a good amount of money on this fish, id like some advice soon, he seems to be getting weak...