What's wrong with my hands???

My hands do the same.  I've figured out that forcing my fingers together to form a bladed hand causes them to cramp up.  This went away once I started swimming more. 

you may find swimming still stressful/worrysome/scary (even on some tiny subliminal level) and thus you're putting great force on your hands.

sorta like when people curl their toes at the dentist.

that always makes me laugh.

Finally. I have found a malady that I have yet to endure.

It may be too that your hands are just tense the whole time you're swimming. Try shaking your hands on your recovery, making sure they're relaxed and loose on that part of the stroke.

Try doing some laps with closed fists to get teh feel of your forearm creating surface area to help anchor your arms in the water. Do 25 fist and then 25 open hand trying to keep the forearm feel. Youre hands should start to relax.