I ve had mild left shoulder pain for 6 days. three days ago ran 6 miles, had shoulder pain but subsided when soaked in hot tub with Epsom salts. 24 hours ago, ran 5 miles and shoulder pain was excruciating; pain went up the trapezius, then worsened, went up to neck, until pain was so bad I started to hyperventilate. nerve problem?-bursitis? tendonitis?