Noticed it about a year ago, looking like in an insect bite (had a dozen all around my body, been in a rural area for a few days). Located in the
back of the knee, exactly where the
skin folds. Started as 6mm, now around 13mm in diameter. Affected skin got very thick. Goes from brown to extreme red when it itches, very uncomfortable. It starts itching when knee is bent and skin folds, by sweat, stress or when clothes touch the area.