Answer the questions from the Trouble in the Enclosure sticky here http://www.frogforum.net/showthread.php?t=14721

Pacs can eat a mouthful of cocofiber and it won't bother them. It passes through their digestive tract just fine, so it's not because of that.

The most common reason for pacs to stop eating is either something is off with the husbandry or they have an impaction (intestinal blockage).

I'll go ahead and write out how to deal with impaction if that is the problem, since it's such a common reason for them to stop eating.
Feel the frog's right side; if you feel a lump, then it's most likely impaction. You can help him pass it by putting him in a bath of chin-deep luke-warm treated water with several drops of honey in it. If it doesn't freak the frog out, you can also try and GENTLY massage the lump (some frogs are fine with that, others freak out) if he doesn't let you do that, just leave him in the water/honey bath for about 20 minutes. That should help him pass it. If it doesn't, you can do the honey baths daily until he does.