My lizard is sick! Is it because of the sand?

My pet lizard had a problem years ago where the sand accumulated in his stomach and it cost $300 for the medication to correct it. He did fine with edible sand, but a few months ago we changed it to very fine sand. Now he's gone down hill and won't eat. :/ he's a mali uromastyx. He's shedding right now and has been sleeping 24/7. At first I thought he was hibernating. Is this still possible???