Well, here is yet another shoulder pain topic.
I am a Massage thereapist, not a Dr. and as such I can't diagnose. I can asses however. From the info you have given me here, I suspect that your suffering from some inflamation due to repetitive strain. What that means is that your over using your shoulder. I don't think it's just the shooting, but the combination of your work, shooting, and probably things your doing around the house. In other words, yes your shooting to much.
My profesional recomendations are this:
1. cut WAY back on the shooting. (at least for now)
2. Ice your shoulder for 20 min noon and at night.
3. Gently stretch before shooting AND work.
4. visit your Dr. to make sure it's not some thing worse. i.e. impingment or torn rotator cuff.
5. GET A MASSAGE. If you need a recomendation, pm me and I should be able to find some one in your area, or if your super rich, you can fly out here to Oregon and I'll work on ya. =D
Derek Wrigley. L.M.T.