2 days in to my toddler taking amoxicillin 4 ear.he grabs his booty in pain. he won't put it in bath water. it's all red. allergic reaction? wat 2 do?

Possibly: In general allergic skin reactions to antibiotics are more generalized and tend to be itchy. They are often red blotches that can vary in size and briefly turn white if you press on them. A bottom or genital area that is all red and more painful is more likely a yeast infection that has developed as a side effect ( not allergy) to the medication. An anti fungal cream will likely be needed.