iamkickstand wrote:sounds more to me like a shoulder weakness problem than a bike fit problem.
Do you do any sort of strength training off the bike?
Good suggestion to look into, if nothing else to test the shoulder. There's a few exercises our football team used for people who had a tendency to hurt their shoulders and it works wonders for preventing repetitive injuries. Use incredibly light weight, it will surprise you how little you can actually lift when your arms are fully extended. Might be better to use no weight and do timed reps. Like hold your arms straight out from your side for a minute or so. Sounds easy, but I hated doing them. Same thing with arms out in front, though it sounds like your pain is more of the rotater cuff. A good exercise for that is to have your elbow straight out from your side and bent at 90 degrees and then rotate your arm forward and back up in a slow controlled motion. Again, light weights, even the guys that could dominate the bench press with 400+ pounds couldn't get higher than 25 or 30 pounds dumbells for the rotater cuff exercise (not sure on actual name anymore).
Going to a doctor is always a good idea if you have a persistent pain. Having said that, I hate going to the doctor and refuse to go if I can still do activities, even if there's a little hurt, so I don't follow my own advice here but that's the advice I always get when I do something stupid and the pain lingers for more than a few weeks.