Lightning has a blockage in his intestines. The vet doesn't know if it's a foreign body or a kink. He's keeping him overnight and will do a barium study tomorrow. If nothing goes through, then Lightning will have to have surgery.
Lightning is a greedy eater, and I'm guessing he's snarfed up some fibers or something and is paying for it now. A blocked intestine is a life-threatening disorder. Prayers would be appreciated.