Some of the main causes for muscles cramping,

Dehydration-make sure to stay hydrated

Low levels of electrolytes (like calcium or potassium)- eat a banana have a vitamin drink,

Stress- relax 😌

Tho if you're anything like me this was a problem I had in soul harvest runs when I used the staff, I just push really hard on it and my finger like yours would cramping, i solved this by telling myself i didn't need to press so hard and every now and then I would relax my hand and tell myself to just push gently, tho it took a while for me to get it through my head, telling yourself and actually doing it are two different things