My son was bitten by a dog a week and a half ago. Supposedly the dog was up to date on it vaccinations. The bite occurred on his thigh and the puncture was deep. He did not seek medical treatment. He has been keeping it clean and started taking an antibiotic a week ago to ward off possible infection. The bite is slowly healing. But, after the bite he developed a itchy rash of little red bumps that started near the dog bite and has spread the entire length of his leg and partially on his forearms. It is not spreading anywhere else- but the rash will not go away. What are the possibilities causing this? Thank you.