Recently my younger brother (he's 13) has been clinging on to, he literally won't leave me. The only time he's not with me is when I'm in the bathroom. So I finally asked him what was wrong and why he's being so clingy and then he told me that he kept on having nightmares that I was going to die and now he is absolutely convinced that I'm going to die. How do I convince him that I'll be fine and that it was just a dream?