Left arm & fingers hurt during exercise, even walking. no chest pain. thoracic outlet syndrome negative, normal stress test & echo. what could be cause?

You had an unusual work-up for the left arm and finger pain. I wonder if you have pain of the whole arm and all fingers or just some parts of the arm and hand.

A possibility is an atypical manifestation of carpal tunnel syndrome. Your tests ruled out 2 possibilities. I recommend being evaluated by a hand surgeon or an orthopedic surgeon.

If no prior EMG/ NCS, suggest this be accomplished. And next step, hand specialist!