The vet was really great and talked to us for a long time. He said he feels like it is usually a nutritonal issue when this happens. He said it may be from lack of calcium, intestinal worms (which he is being treated for.....he could not get a very big stool sample to test), or dehydration.
We are also going to keep him on paper towels for a while so that we can make sure he is not bleeding etc., and then we will probably move him back to reptile carpet until he is really a stable big adult. The sand is just not worth it for me.
He also said we only need to feed him 2-3 crickets/day for the next two weeks or so while he is on the special nutrient mix. He felt like the exoskeletons on the crickets may interfere with his digestion. I am going to order some Phoenix worms in a couple of weeks and try him on those for a while.
Poor Charley. He looked SO much better this afternoon when I went to get him at the vet though.