Yes he is wormed regularly, and is drinking like normal (well his normal) he love drinking straight from taps. LOL. Thank you for putting my mind at ease for tonight .
Do you worm him regularly? if not, do so. that might help. if he's fine otherwise, just keep an eye on him and bring him on long walks, to aid his metabolism. if he doesn't eat for more than 3 days, I'd get him checked by the vet. Also, keep an eye on how much he drinks, as drink is very important if he doesn't eat.