question: I was walking outside in the pasture and started feeling a stinging feeling behind my knee. As soon as I reached down I could feel a lump the size of a quarter. I took my pants off to let my daughter look at it and she could see the lump was turning purple already. I walked into the house and showed my husband. By this time, less than five minutes the lump had hardened and ran along the vein creating a long hardened purple bruise about one inch long. I put Benadryl cream on the area, but it continued to stay swolen and purple. Any suggestions?