Is your rash healed? Could this be a case of dry skin? I always find that after the rash is mostly gone, my skin is pretty dry so I have to slather on a good lotion.
Something else to consider is that stress will cause a release of histamines which means more itching. Here is an article I wrote back in 2003 in response to someone else who had a rash that wouldn't go away:
I know this sounds weird but in the last several years, I do nothing when I break out from poison ivy contact. OK - I don't quite do nothing what I do is work to keep myself cool and calm. If you stress over the itch it just seems to get worse.
I hope this helps. I know that the itching can at times be insane. But it will pass.