It can point towards parasites but usually (especially as he's been checked) is down to diet, usually veg/fruit in particular. What fruit do you offer? and how refularly? The tip is usually to remove a veg one at a time from his diet until you pinpoint the one causing the issue, however this may not be the case seeing as you say he doesn't eat it! Is there any changes to his diet at all? Has he always had the livefood you offer or has 1 been introduced recently? Maybe a more detailed explanation of his daily diet will help.
He could just be extremely hydrated I guess, I don't know what else to think other than diet or parasites. No help really am I!