Since I used the mouse for decades the transition to the track pad and scrolling across the ipad and iphone are very foreign to me. My son keeps telling me to relax and just gently tap the device instead of jabbing it. My hand and fingers are very sore too. I've been completely Apple for 7 months and about 40 years too late.
I'm going to try wrapping my hand around the knuckles to practice gently moving my fingers.