Yue, your case is definally NOT an identity crisis. It could be chronicle depression, but not identity crisis. I think it's more like the winter's coming messing with our hormones. I'm having the same kind of problem here and my French teacher (who is a man) told me that it's normal and it happends to everybody. Winter's arrival makes people melancholic and unable to feel happiness. Guess it'll settle once winter is fully here: snow = joy!