Aw, poor Henry Cat, and his poor owner! The only thing I would be worried about would be him possibly having eaten string or a rubber band, or something like chocolate or poisonous plants of course. Otherwise my experience is that cats are very careful with what they eat and will leave food that is "off" alone. He may just still have a hairball waiting to come out that makes him feel queasy.
I get worried when our Lyra is lethargic too. Luckily I'm learning that she's a bit of a hypchondriac, so it doesn't take much for her to huddle down and feel sorry for herself. She's usually bouncing around a day or two later.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett