I had a similar problem a few years ago, and it got very painful.
I think Jeri and Alan have it right about washing the hands.
I changed to Ecover detergent (made from Palm oil) and the problem cleared up.
The problem was severest on the fingers of my left hand which every couple of days; I use to clean my glasses, with detergent. I'm still doing that with the Ecover and have no problems.

TTFN
PP