I am sure this post won't do anything now since your dr. apt is for tomorrow. It's really hard to diagnosis without the proper equipment such as X-rays. There are a number of things that could cause shoulder pain. Although, because of his line of work it sounds like something caused by injury from heavy lifting. Bursitis can be caused by the slightest lifting, even lifting groceries into a car could do that. Bursitis can be treated with ice compresses not heat. Anti-inflammatory medications such as aspirin could help. It could be anything. Here are a list of conditions that can cause shoulder pain: Bursitis or Rotator Cuff Tendonitis, Rotator Cuff Tear, Frozen Shoulder,calcific tendonitis, shoulder instability, shoulder dislocation, shoulder separation, labral tear, SLAP lesion, Arthritis, or Biceps Tendon Rupture. Therefore, the best solution is to see the doctor which it seems you're making that step so good thinking. Hang in there and try to be patient with him, remember he's in pain, he doesn't mean to be annoying. Good Luck!