Why haven't the parents taken care of this? Why aren't they providing cream or an explanation for you? Why haven't they taken him to the doctor? Those would be the questions in my mind. You are not the parent and therefore not responsible primarily so ask them what they are going to provide to treat the problem for relief for their son and don't worry any more. I don't put any creams on a child unless they have been bought and provided by the parents. Some creams if used on the wrong type of rash will only do more harm than good.