Good day. Could you please tell me what it could be? It might be a ras…

Good day. Could you please tell me what it could be? It might be a rash or an allergy... although nothing specific is in my diet, I'm breastfeeding. And he constantly scratches this spot while sleeping... What have we tried! Nothing works, it will just go away, but he keeps scratching again in his sleep, I don't know what to apply anymore...