As the old saying goes, Rome wasn't built in a day. It'll take time, but if you are ready and willing to change your arm slot, drop down to a full sidearm delivery, I can guarantee that you'll be able to pitch at near-full capacity with little or no trouble with your arm and shoulder. The sidearm delivery is the easiest and most natural of all the pitching deliveries and posts no problems with the shoulder and arm---I should know, because I was a natural, honest-to-gosh sidewinder in my playing days, and Although I didn't have much of a fastball I had a pretty extensive arsenal of breaking and offspeed pitches---my two best were a hard slider and a very good knuckle-curve.
I would suggest two things: first, get in touch with a good pitching coach, perhaps a professional pitcher who throws sidearm, and have him work with you and help you get the hang of things. Second, check out a website called "Sidearm Nation.com"---I'm on it a lot and there are plenty of folks who throw sidearm and submarine; you'll get a lot of good tips, especially if you read the interviews with a number of pitchers. Oh yeah---if you can do so, learn about the crossfire and how to use it. This is a beautiful and lethal move that works only with the sidearm delivery, and if you can master it you're going to be lights out on the mound.Any more questions, feel free to ask---I'm no farther away than this stupid computer. :baseballpitcher: