I am a reservist who got hurt on active duty time and need help?

I am a Marine Corps reservist that got hurt at MOS school in early 2008 and again at annual training summer 2008. It is a jacked up shoulder. After following up with it for quite a while(months) I got knowhere and dropped it. It has over the last 3 years flared up and got worse and at times it goes away. Our corpsman have told me that claim got kicked or it is no good but i have been to medical and got documented. Well now it is a serious problem. I dont know how to go about getting it taken care of(do i talk to my units medical ar just go to a VA). I cant afford to go to pay and get it looked at and fixed out of pocket for the marine corps to maybe decide to pay for next century. Please help me get started with this process and not stack up medical bills