Suggest Remedies For An Itchy Bump On My Leg

got an itch on my right leg to the right of my knee, then it felt like a burning sensation, looked at it and noticied it felt like a bump and immediatly starting turning purple, that was 4 days ago and now there is a big 3 inch round of a dark purple bruise, No pain but I'm a lil scared not knowing, I have no health insurance.