What's my friends problem??? why is she treating me so poorly?

(ill try to keep this short) soo i have this friend.. lets say her names AJ. so Aj is constantly putting be down but not in a direct way. for example i am a really REALLY great musician and i think i'm pretty talented and on my friends fb wall i made her a cover of a song she really liked for her birthday.. her uncle from north carolina saw it and talked to the friend about gettin me a record deal as a music producer.. and i mean hes made some pretty famous people.. well famous! soo i was super excited!! i tell AJ and she goes "ohh... well dnt get your hope up." and i'm like ITS A RECORD DEAL! and shes like "calm down... God." all unexcited not tthe least bit happy for me. I tell her about a guy i really like and how were on the verge of going out and shes like "ik he seems really great but i mean he's probablly just another guy.. a loser even? dude you just met him..." and im like actually ive known him for 4 or 5 years??? we were just friend though then and shes goes "alright" thats all she tells me.. and shes not a pesimistic person!! its only when i tell her something AMAZING!! which is very rare but she really puts my hopes down. and its not like she doesnt have it great. she goes to a professional highschool for arts because shes training to be a prefessional dancer. Shes soooo pretty! almost every guy thinks shes super hott so i'm not sure why shes getting on me like this. She doesnt act like this for other people!! and i'm not bragging im just sharing and then i usual drop it.. ugggg someone explain?