PLZZ HELP!!! MY PARAKEET!!!?

ok so i am really worried about my parakeet and i dnt know wat to do! i just came down to see my parakeet and it is acting really weird, its wings r spread out and it wont use its legs and wen it moves it is trying to fly in stead of walking using its legs, also it keeps on chirping, and it sounds like its in paine or something. i have had this bird for a lil more than a week and i havnt had any problems with it. can someone plzz help me i am really worried about it. wat shuld i do? does anyone have an explanation on wats wrong? thx in advanced for any help!