I'm guessing your friend has been in this condition for quite some time now. And of course when you say she is under watch that means she would be under heavy medications. Is she also being given ECT? Nose bleeds could be a side effect of that kind of therapy or one of the medicines. So it would be best to get it checked with her psychiatrist or get a second opinion on her therapy. Your behavior towards her should be empathetic and caring. Listen to her and try to keep her engaged in productive activities.