Recently (about 3 to 4 weeks), my arms have been growing little pink spot. After an hour or so, the spot spreads to the surrounding area and after a few more hours, it disappears completely. The area is normal again. Then again, there's a new spot. I'm not saying it happens as I said it. When whatever that thing likes, it pops up, has a pink itchy (just a little bit itchy, but not painful at all)spot and spread again. About 1 cm. Then the next morning, I wake up, it's gone. I dunno if it is harmful or harmless. I don't know what illness this is. I'm just a 15 year old who is worried about this problem, please help me. Thank you.