From another extreme PI sufferer. In addition to the benedryl recommended by doctors, I have had success taking a hot bath with alpha keri bath oil. Very soothing when the itch becomes unbearable. Pat yourself dry very lightly so as not to remove the oil.
Something that I plan to try the next time I have a major exposure is goats milk soap with jewel weed. I've had a person swear it works to reduce the breakout when exposed as well as reduce the discomfort when a breakout does occur.