Excuse me, what's that on my leg?

Is this an allergic reaction to something? I tell you never to underestimate the little red dot on the skin, which may be an exposure signal of problems in other organs of the body. However, in the face of such a situation, please don't worry too much. Don't believe the exaggerated statement on the internet, just sit in the right position and think that you will be terminally ill soon! Physical problems are not that you can't search online, but you must treat your answers dialectically. Well, I'll give you a heads-up. I hope you will never need it. Let's hurry to the hospital!