Lower back pain. And again comes back.

I jumped in an event around 2.5 months back. I heard a click sound in left side of lower left backbone and since then I am suffereing from pain in that area. When I press the area I can feel the pain and also while and bending and doing other physical activity. I have done MRI and X ray and nothing significant has come in it but the pain dosent subside and increases with physical activity. I am undergoing compulsory training at armed forces which gives me no rest time. I am somehow continuing my training with this pain. I also have a precondition of ankylosing spondylitis. I have taken many anti imflamatory medications and pain killers in these past 2.5 months but pain relief is temporary and again comes back .