Dislocated Jaw

[UMreefer]

I have a Green Chromis whose stomach got a little to large for his eyes...or rather his mouth actually and he has been swimming around my tank now for about 2 days with an extended mouth...it looks like his jaw is dislocated. He is still eating by almost just inhaling the food but it just looks painful. I am trying to get a picture of it but the little bugger swims really fast. Has anyone dealt with this before, I have seen these fish do this before but normally they pop it back into place after a couple of minutes.

Any insight would be great, thanks.