Could Possible Compressed Disc In Lower Back Be Serious?

Hi I'm a US Marine during my first deployment I was in a helicopter that went down afterwards I saw my doctor and after evaluating me he came to the decision that I had possible compressed a disc in my lower back he wanted me to get X-rays I refused because if I had I would get medically discharged from the military and a job I love after we got back stateside I had lost an inch off my height bout a year later I went to aphgan for another deployment and no change but now stateside again I've lost a nother inch over the last 5 months when I joined I was 5 10 after Iraq 5 9 now I'm 5 8 flat. My question is could this be a serous problem worth getting forced out for or is there greater possibility that it is minor?..... I was 18 when I joined and 22 now I just started my second enlistment of 4 years im higher ranking now and don't do very much labor any more