Hello, thank you for consulting with healthcaremagic. As you are mentioning that your son is having itching sensation in tongue and there is some red colour bump present in the back, it looks that your son is having oral thrush. Actually it is a common condition which occur in infants and toddlers. It occurs because of improper oral hygiene maintenance in them. In this condition a white area occurs in the mouth and tongue and when you scrape that white area below it a red itchy area is present. Better you should visit a pedodontist ( child dentist ) to get it treated. As only medications is not the treatment. Hope it will help you.