Not sure if it's relevant, but I remember having very sore hands for months, maybe 18 months after I started paddling back in the day. I still get soreness in the finger joints sometimes.
I try to relax my hands when paddling now - make a conscious effort to do it every now and then.
I use racquet handle tape (as in squash or tennis racquet) on my paddle shaft - on the right ie my controlling hand. I find that makes things more comfortable and my hand doesn't slip. It does tend to cause blisters though if I haven't been doing long paddles.
But yes, beginner paddlers often grip the paddle too hard.
I hope your hand heals fast...
Rob
Currently Epic V10 Elite, Epic V10 Double.
Previously: Swordfish S, Evo II, Carbonology Zest, Fenn Swordfish, Epic V10, Fenn Elite, Red7 Surf70 Pro, Epic V10 Sport, Genius Blu, Kayak Centre Zeplin, Fenn Mako6, Custom Kayaks ICON, Brian's Kayaks Molokai, Brian's Kayaks Wedge and several others...