Thank you for your query at DoctorSpring.com
I understand your concern.
Yes, I can appreciate the spreading rash which look like hives. In absence of any trigger, it is difficult to understand what is causing this rash. However, I will advise him to take Tab. Claritin ( Loratadine ) 10 mg once daily at bed time, besides the application of Calamine lotion on the rash affected areas, for 3 days. Let me know, if it comes down on taking Claritin and you can follow-up.
Hope this was helpful,