Sharp nerve pain in the right index finger had a pen cap pressed over the same finger few years back. Is it neuralgia? How is it treated?

Have your vitamin b12 level test done first.

I am sorry to hear about your concern but will be happy to assist you. You may experience pain if you straighten your fingers because of radial tunnel nerve syndrome. This may occur especially on the back of your thumb and on your index finger. Your radial nerve may experience pressure near the elbow, causing symptoms in the finger. Let's connect over a call so that we can discuss your concern in details and make a suitable treatment plan for you.