My 8 year old son (63 lbs) has had 2 bumps come up on his knee a few days a part. The first one popped (like a blister, w/ clear, yellowish discharge) and left a redish rough spot, the other popped up and has been bledding. They grow in size, rapidly. The 2nd is approx 3/8 in diameter. The first now looks like a pink circle. The doctor placed him on an antibotic by mouth and a cream. She said that she believes that his body is having an allergic reaction to a bite or something he came in contact with and placed him on the medication to prevent staph infection. She said that it would also treat if impetigo. He is allergic to seafood and environmental things such as grass, dust, etc. Any advice?