First: I am having a lower back pain since one month I used to gym regularly now too .Before I used to get pain but after few days it goes but this pain now doesn't go. Its not a continues pain. I get it when I sit comfortably and when I stand I get that pain and to lessen the pain I lean back and stretch . Second: I get this pain in keens, extreme pain when I jump or I carry weight down stairs or if walk on a slope also when I sit on my bike and push my self forward.