My friend is very good and cheerful. Earlier, I was under impression that she is really very happy and sensible. Once, I started talking to her and spent time on phone then realized that she suddenly becomes upset without no reason and starts behaving like she has several issues with the person she is talking. The sudden changes of her mood really disappointed me a lot...Sometimes, she is so happy and in next couple of minutes she becomes so sad. I am worried about her career because one who is close to her can understand but one who are not then they can create wrong perceptions about her. Does she need to contact any doctor or its temporary problem? Please help.