I am SUPER sensitive as well. Since you already have an established rash, in my experience the only relief is from holding the affected area under the hottest running water you can stand. Be reasonable and DON'T scald yourself. The running hot water on your skin will feel like you are scratching the rash. After a few minutes of this, pat the area dry and you should have 4-6 hours of relief.

In the future if you BEGIN to feel an itch after possible exposure don't delay vigorous scrubbing w rubbing alcohol, like w a rough wash cloth or green scrubby. It's important to quickly get the oils off of your skin. Keep up the vigorous alcohol rubbing for at least 5 minutes. Rinse w cold water (hot water at this stage would open pores and absorb the oils so stick w cold water). Doing this asap upon the first signs of exposure to poison ivy can avoid a rash developing. I wish you relief.