Not trying to be funny and if you're being serious, you might check in the toilet tank, under the lid on the back by the wall. It's a stretch but given the size you mentioned him as being, it's possible he could have shoved it up enough to get in there. Otherwise, I'd start checking in drawers as in taking them completely out of the cabinets and looking in any possible conceivable place he might have curled up if you're positive that he couldn't have fit under the door. Tear that room apart and completely eliminate any possible hiding spot before you expanding your search would be my advice.