What Causes Sharp Pain In Left Chest Along With Numbness In Left Arm And Shoulder?

I ve had a needle-like travelling pain in my left chest/shoulder blade 2x in the last couple of weeks.It s left my left arm crampy and my left shoulder blade in back feeling funny...a little numb, crampy.I went to walk-in clinic to be sure it wasn t a blood clot, heart issue. They did an ekg and my heart is perfectly fine. I ve been walking up 5 flights of stairs on my lunch hour and no problem with my heart. What should I do? Do you have any clue what this could be?I ve had these attacks for many years, sporadically, but no one has been able to figure out what they could be. These last two: the first one was excruciating needle-like pain where if I breath in, it travels more...also, it s the worse one that I ever had...even went up into my neck and down my left arm...I was quite sore on left side after it and then I had a more mild one this week.