Freind Problems?

Ok so I have this freind pretty much my best freind known him for 3 years recently hes been acting weird with random "*****" hissy fits and the stuff he gets angry at isnt even that big. He ll start off happy in the morning on somedays then towards the evening he starts to get agravated with anything he can just to get aggrevated, but me benig the freind i am dosent like to see him all crabby or what ever so ill ask him whats wrong verbaly or in a note (high school) if i ask he says leave him alone if i wright a note that he ll rudely throw back at me and embarres me in cl. It really satarting to take its tole on me i ve reallt hard trying to talk to him about it even when hes happy. Lately ive just been egnoring him when he gets like that and just hang out with other freinds. Then the next day he ll come back happy and energized but after his previous day i dont even want to be bothered with him, and TRY to give him the same treatment but i end im braking in within min. and were