My Son Rode The Elephants In Chiang Mai And The

My son rode the elephants in Chiang Mai and the next day noticed a rash that was on his lower leg that was weepy and itchy. He put neosporin and cortaid on it and it improved over the next week of travel. Three weeks later the leg raise is almost gone and now the rash is popping up on his torso and spread all over his back. What do you think it is? He of course is now back at college without access to a car.