Ooh I suffer with that really badly (to the point where I've drawn blood I've itched so bad).
Stay out of the sun, drink lots of cool drinks and keep your body cool, I would recommend keeping a damn towel nearby to stop your body getting hot. Put some shorts on or something to cool you down.
You can get E45 or Sudocrem which will help a little. Unfortunately there's nothing a doctor could do for you so keeping yourself from getting warm is all you can do.