Stress at work...pain in second finger

I am having severe stress at work. One of my coworkers acts out (literally like a child) every time our team leader goes on vacation. She also constantly shares how she has CNS disorders (she was constantly twitching and shaking her head and arms and legs-also very disturbing to other coworkers as well), she lied about getting the Covid vaccine and she feel the need to narcissistically turn EVERY conversation back to her, her life, her son, her medical issues, etc....(gosh, even writing this out makes me feel better).
It got so bad that Friday morning (after a hellish Thursday with her making a personal phone call in the MIDDLE of a situation that we all should have been dealing with, my middle fingers (the ones used for certain gestures) started aching at the joint. On each hand! I didn't even think about TMS, but then I read a little Sarno and sure enough, that is exactly what it is!!!! Tomorrow I am pulling her aside and telling her that I will not allow her to be demeaning and rude to me anymore. My other coworker said this, "You y