What Causes Fingers Coldness And Numbness With Discoloration?

my fifteen year old daughter was complaining about her fingers being cold and numb and when I saw them, they were completely white. after a few minutes they went blue/black before turning red. After looking at pictures of other people with raynauds, I know that she has this. However, she has problems with her knee and back - she says it 'cracks'............does she have another conditions in relation to raynauds ?