It looks to me like he's playing with you. Maybe he likes making you jealous because it gives him a positive reassurance that you like him and don't want to lose him. A previous girlfriend of his could have done the same thing to him in the past and he wants to feel macho by know that other girls love him "not only you". And if that's the case then he is really immature. Have a heart felt talk about it with him and let him know if it bothers you?If he keeps doing it, then he simply doesn't care about how you feel, but how he feels.
Make yourself busy...don't overly ignore him but show you're not completely drooling all over him. If he wants to go out with you say you're busy and go out with your girlfriends. Laugh and have fun with your girlfriends or with other guy "friends". But DO NOT OVER DUE IT. He will notice you then. And probably won't like it, generally he will want more time with you instead of the other girls. Most guys would get the picture and turn to you instead of other girls after that if they truly liked you.
talk to him. figure out what he's thinking. how he feels for you. ask questions.
buy a new outfit, something that you feel confident in. and for hair if you usually wear it straight, try curly, or curly try straight. try braid it. pull some hair in a clip. try a poof or bump or whatever they call it. pony tail? bun? aha I don't know try something new.