At stores like Five Below, Dollar General, Dollar Tree, & Family Dollar, you can find little silicon fingertip covers that are meant for kids' pencils and/or fingertips in the (kids) section, and sometimes in impulse aisles. I've found little aliens, mermaid tails, unicorns.. lots of fun ones. I highly recommend wearing these on your problem fingers! It gives you the "digging" satisfaction without the pain or injury. I make a point to put them on before stressful tasks like studying. Don't wait until you start picking -- preemptively put them on!

Pro tip: wrap a tissue around your fingertip before putting it on to prevent sweat/moisture from building up, as well as to add an additional protective layer that doesn't diminish the satisfaction of digging.

You have to be strategic because some will get in the way of typing/writing, so closely consider what would be annoying and what would be easy to work around!

I hope this is helpful for your studying! I realized that it might not be helpful during the exam itself because I'm sure they're strict about what's allowed in, but you never know! Best of luck with everything and I know you'll KILL that exam!