I agree with Mrs_Savas. She has a great point and you need to provide more info hun. Looks like it may be either some skin condition or a diet related issue. Check on his diet. Is he allowed to go outside?
Hi,
Is there any change with his fur or skin, especially around his head? Are his bowel movements normal in appearance and frequency? Any changes in his diet - what does he eat? Is he an indoor only or an indoor/outdoor cat? Are there any other animals in the household? Is he overweight?
Sorry, but I need to know a few more things before I can really address this.