Nice of you to take the poor thing in ! The drinking is a good sign, and if he will take Pedialyte, you may be able to get something more substantial in him. There is a product called Oxbow critical care that you can order on-line, another thing to try is to make a "smoothie" type mixture of greens and bugs that is watered down so that he can ingest it more easily, a couple times a day [ hopefully]. It will probably be touch and go, but at least you are trying. I would also keep the other animals out of his view, he needs to have his energy to help fight back from his pitiful condition, undue stress will make it worse.