Even though I am not a doctor, some illnesses I can diagnose by just using common sense. I went to visit a friend of mine, and he was feeling fine until he saw an insect in his house. He immediately started feeling dizzy, his temperature rose, and he felt nauseous. When I visited him a day later around the exact same time, he was feeling better, and the insect we previously saw had just died. That’s when I concluded that he had a 24 hour bug. (I often impress myself with my analytical brilliance).