When I write, my index finger digs into my thumb, which ultimately causes horrible cramping. How can I avoid this?

I write a lot in school because of honors classes. Recently, I’ve been experiencing this issue more frequently, but as I get worn out from writing, my hand cramps like crazy. I have to stop everything I’m doing from the burn, and my hand starts shaking. From the way I hold my pencil I guess, I always have crescents and dents in my thumb after writing, leaving it red. Before anybody says I should try writing with a pen instead of a pencil, that also does me no justice lol. I’ve also tried cutting my nails short, but again, no better result. And I tried finding a different way to hold the writing utensil, but I can’t get used to it, and Im still in pain from holding a pen. As of now, I’m using a bandage over my thumb and index as a temporary fix, but I don’t know any alternatives. If anybody has advice on what I can do to prevent the pain in my thumb/dents from happening or cause less pain and cramping, I’d really appreciate it!!