I'm not a vet but AM a pharmacist and fill scripts for customer's pets all the time. mari1988 is ABSOLUTELY correct; if he is growing (which you said he is), then he's getting enough carbs and protein but could still be dehydrated. Cats, unfortunately, don't have a very efficient renal...
Since your post about your cat's weird reaction to diazepan was dated some time ago, by now you've seen that the symptoms have disappeared. However, a LOT of people give tranquilizers to pets without consulting a vet about the proper dose, possible reactions, etc. Many people aren't even aware...