I got a mosquito bite yesterday, and it is now swolen to maybe a 2×2 inch area and the skin is very hard. It also stays depressed for a long time when I press my nail into it. It’s a little painful and very itchy. How come some mosquito bites (and I know it’s a mosquito because I saw it bite me) become so painful and large, and other ones are just small bumps that itch with no pain?