Hello,
It could have been due to bruise after trauma. The blood under the skin which causes the discoloration of bruising should be totally reabsorbed by the body in three weeks or less. If it persists beyond that, then it should be evaluated.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
so it appeared to go away within a few weeks, but more recently I can still see the shape there. sometimes maybe a little bit of a "sting" (for lack of better description). It doesn't really hurt to touch it but there is some strange sensation there. For example, if I get startled and my skin suddenly "chills" -- well, i feel a stronger sensation on the side of my knee. I know I need to get this checked out, but any clue as to what I might be looking at here? I like to be prepared with questions when I go in or at least a general understanding of what might be going on. Thanks for your help.