I take ibuprofen before we leave for the day, and I switch shoes every day. I take my allergy meds before dinner.
When we take our breaks back at the hotel room, I draw a bit of cold water in the tub and stick my feet in it. Rinse my legs from the faucet for a few minutes with the cold water as well. Then I lay on the bed, with my legs elevated (using the blanket or pillows or a jacket bunched up) for a little bit.
Since I started doing that, along with a good covering of sunscreen, I haven't had a major reaction.