I have got the same problem! Well, you could book a sports masseuse, but this really does hurt. What they will do is warm up the affected area with some oil and rubbing, then slowly build it up and effectively strip down your muscle fibres linked to the tendon.
Tendonitis is cause because of overuse of the muscles, which in turn causes a slight shrinkage. This tuggs on the tendon, causing it to inflame. Essentially, your body is actually doing you a favour by telling you that you are not doing something right, or need some rest/stretching. Make sure you effectively warm up before a game, doing stretches and getting the blood flowing to the area. Take it easy however, as you may need to strengthen the joint too, so take a little break from bowling, and do non-weight bearing exercises, such as pulling a bungie rope. Make sure that you try not to do weights with it.
I would strongly recommend the muscle masseuse first, as it will hurt for a few days, but aid significantly in the recovery. This can be expensive though, so make sure you ask them to check on any other tight muscles or niggles, but tell them to focus on the shoulder! I really hope it gets better, as I can understand your frustration being a pace bowler myself! (Only around 65mph, so not right arm rapid) You are still young though, so rest up and heal fast. After it heals, I would recommend you continue with the joint strengthening exercises and also pressups. Make sure to stretch off beforehand!
Hope this helps!