Tiny, Red, Itchy Bite Mark On The Knee Which Is Dry And Looking Like Ring Of Little Bumps With Indented Center. What Could It Be?

About a week or two ago, I thought I had a tiny mosquito bite on my knee as it was small, red, and itchy. I thought it was going away because I didn't notice it much after a couple of days. I noticed it yesterday, and it almost looks like a different thing all together. It started itching like crazy again out of nowhere and I noticed that the center of it was very dry, and looking more closely at it, it almost looks like a ring of little bumps and the center is slightly indented. That part of it is about 1 cm. Surrounding that my skin looks lighter as well and the whole thing is about 1 inch, including the "bite" part.