Triathlon Jellyfish Update

After the triathlon i knew the memories from the race would stay with me for a long time to come. I never thought that my jellyfish stings would too! I woke up this morning with a crazy rash/reaction from exactly where the jellyfish got me on my left arm and right elbow. Some quick internet research explained that this is a common experience. The reaction can last 5-30 days after the initial bite! OUCH. Anyone have suggestions on how to treat my arm?