Well if he just ate then that's normal my snake is always quite dormant especially for a large meal. It's actually mouse night tonight for me! Um, it could be a small case of lethargy (staying still) and just type the symptoms into the net. If he like, NEVER moves within like, 2 days, (make sure he's not dead) take him out see if he'll crawl around. Check for other signs of disease--foam in the moth or nose or eyes, open mouth,(like, halfway dislodged,) misshapen lumps on the body, other than the lump the mouse might make in the belly) if you feel a rock-like lump near the vent (rather larg-ish--if you can't notice it by just looking don't worry about it---it may be constipated. If this is so, bathe him in shallow water for half an hour (watch him the whole time) as soon as he poops take him out. If he doesn't get him to crawl around on your hand a bit more, then put him back in his tank and leave him. You'll probably see poop soon. If the symptoms are extreme and he resists moving at all, take him to the vet ASAP. But be prepared to pay $150 dollars or more. For just a check up for me it was $120 bucks. She had said 80-90 bucks, but THAT flew out the window.