Yesterday I noticed a large blue hard lump on my inner wrist- I was folding clothes, I was not bitten by anything that I know of, and I did not hit it on something at least not that I remember. The swelling immediately went down after I noticed it. I took two Benadryl just in case it was an insect bite and iced it. Today it is still swollen and bruised but not nearly as bad. It does not hurt unless I touch or press on it but it still very bruised. What could this be? I recently started a pole fitness class but the last one I went to was Thursday.