Hi Deb...
My hands have done this off and on...
I've hand my hands curl up so tight that they were even causing my wrists to curl...
I know this will hurt...it did me...but, you have to keep moving your hands as much as possible... AND stretch them as close to flat as you can get them---stretching worked best for me while in a warm bath...the warmth helped ease the muscles/tendons/ligaments.
A friend of mine suggested holding on to a ball... bigger than a tennis ball does best... I often used a 4-5 inch nerf ball....

Abbie
Doing this has saved my hands from a permanent curl...
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niece Ashley!
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Rest in Peace
3/8/90 ~~ 4/2/12