I am 16 years old, and for a while, I have had this thing where usually after a decent amount of activity, like running or riding my bike a reasonable distance, but sometimes, even randomly, a spot on my body, usually on my back or my shoulders, itch really bad, but it isn't really a normal itch were you scratch and feel relieved. Its just like an itch where you have to scratch or else it drives you crazy (I know it is a bad description, but I don't know how else to describe it). The thing is though, after I scratch the spot, it would just move to somewhere else on my body. Either my thigh, stomach, chest, arms, neck, or my back would then have the same itch after I scratch the first spot (back seems as it is the most popular spot). This cycle of moving around would last for about a minute or two, and it drives me crazy, especially when I'm in school. I'm not overweight at all. If anything, I'm actually slightly underweight, I've never touched drugs, and as far as I would say, I'm pretty healthy too. The only thing I can think of is that I do undergo a decent amount of stress, and it could be related to that, but why does it happen during or after physical activity?
Overall, I guess my question would be is the moving itch stress related, or is it something minor, or something more serious that I should look farther into?