I have back 2 back surgeries the last in february 2012 and recently my low back has been popping and cracking when i bend over or sit down. ?

Too soon: It is not expected that you would progress to another level of injury while you are still in your rehabilitation phase from surgery 11 mo ago. This assumes you are still walking 2 miles / day, exercising on hands and knees, stretching daily, and avoiding vacuming or lifting beyond your measured capacity in physical therapy. Check with your surgeon. If vitamin d is low, healing is slower.