Bug bite, sting, or ingrown hair?

I noticed this painful bump on my upper calf about an hour ago. It felt like a bruise, only painful when touched or bumped. It doesn't hurt unless it gets hit or touched, even extremely lightly, and when it does it feel very sore and painful. What is it? I'm concerned about the red ring around it, which is definitely not a Lyme disease bullseye but seems suspicious.