Hello, thanks for using health care magic It is less likely to be an allergy given the duration. Allergic reactions generally improve once the stimulus or stuff causing the allergy is withdrawn. It is more likely to be a skin infection either bacterial or yeast infection. In case of infection hydrocortisone will have no effect and might even worsens the situation. If its bacterial in origin, it will be associated with spreading, warmth and could be dripping. However, he should consider seeing a doctor for an evaluation or try some over the counter anti-fungal creams such as clotrimazole twice daily if the rash is dry and see how the rash evolves. If it improves within a week, then he should continue but f it fails to improve, then he should consider seeing his doctor. Best regards Dr Achuo