Hello
Thanks for posting your query.
I can understand your concern.
This seems like urticaria. It's also known as hives. I understand that you have tried a lot of medications, however I would recommend that you take a combination course of two anti histamines which will help suppress the allergic process responsible for the hives.
I would recommend taking tab. Allegra one in the morning and tab. Claritin once at night.
This should help getting the rash under control.
Please let me know if you have any queries.
Take care