Boyfriend trouble?

Ok i have a problem with my boyfriend, he is really lovey dovey when no one else is around but lately he is being really mean like i was jpking around and asked him if he was getting me something for my b day and he told me that he tought i wasent worth the trouble and he constantley tells me that i have no brains and the other day hei left him messages and he didnt call me back, normally i would just break up with him but im the first girlfriend he has had so i dont know if he is just scared or if he is a jerk please help me.