Oy vey, my little sister is going insane?

tell them she needs help and you should all really go to family counseling...family dynamics are so hard sometimes I have two daughters 17 and 15 and we have had drama like this I swear...part of me wants to say it is just normal teen crap attitude...but part of me wants to say it is so much more...I think maybe if your sister is going from happy to angry in a matter of minutes to happy again she could possibly be bi-polar..and this would have to be diagnosed by a doctor or counselor.. but it sounds like you unfortunately are the only one who is worried and maybe you should recommend counseling tell them you are seriously worried about her..make sure they hear you. good luck