I have sharp, left arm pain since last week. I saw my doctor today and after a physical examination, she said that it's tendonitis.
I work on my computer all day and I guess I overused my arm. The tendon on the outer part of my arm is inflamed. I've been told to rest and take anti-inflammatory pain relievers for a week.
My doctor also showed me some stretching exercises that I can do while I'm working at my desk to prevent this from happening again. I think the exercises are very beneficial.