This sucks.

I have found that stress and water cause it the most.
Although, I have gone to the beach and came back and it was completely cleared up. I actually got in the water for a long time, so the salt water probably helped.

Sometimes I wake up scratching my hands, so I think cotton gloves might be good for me to wear at night.

From Katrina: The scratching was the worst part for me as well, it became unbearable at times. I will try wearing gloves at night too, next time I get it. Hopefully it won't come back.