My child has been sick for about a week. Took him to to doctor 2 days ago for a mild fever at school, vomited once, and been constantly complaining about stomach ache. Doc suggested Zantac, and said it was just a bug it will go away quickly. STILL he has stomach aches, never hungry, lots of diarrhea, no fever, and also has rash/dry skin on his back, by his arm pits.... On both sides. looks weird, not sure if related. He just seems to be getting worse. What do we do?