Spinal extension exercises both passive and active will do.However be cautious not to take curvature seen in x ray or otherwise so seriously ,because it is a result of matural protective spasm .so get Somme and physiotherapy you will be fine.
straightening of lumbar spine occurs because of muscle imbalance in the lumbar spine. this can be corrected by some simple back stretching and few strengthening exercises to totally cure your low back pain.
meanwhile use lumbar support belt when your standing or when going for a walk outdoor.
avoid continuous standing, avoid sitting on floor, most important avoid carrying or lifting heavy objects.
do consult a physiotherapist to have your back pain evaluated and get a demo of exercises and precautions .