i looked for fleas or something but didn't find anything, there hasnt been any changes in his enviorment so i really dont know what coukd be the reason, any idea?
Wow. Could be any one of a dozen different things. It could be food allergies, have you changed or introduced new food recently? When you were looking for fleas did you use one of those fine-toothed flea/lice combs? Fleas are fast and I've often missed them.