Don't Know

How do I tell people that I'm not okay when I don't know what's wrong . . I don't understand why I'm feeling like this tonight . . Maybe because my uncle is passing away and it's affecting me more than I thought it is . . But that doesn't seem like it's affecting me this much . . . Do I have to have a reason why I'm feeling like this? There is no underlying meaning to me feeling down and depressed . . Why does everyone want one? I understand that they want to help me and want to know what's going on, but you know what? I don't know.