i messed up my lower back (from deadlift) last november. i didn't go to doctor. It was pretty bad for first week and started getting better. I finally started to workout again 3 months later. Now it doesn't give me any problem except it is stiff in the morning ( but no pain). After that injury i am very careful about posture and core strength. Hamstrings and core muscle  supports lower back so don't forget to workout out those muscle to get strong back. I didn't evern realize how i used to bend my lower back when i sat in class and while picking things up. But not anymore.

Thanks avi i will definately increase Vit D on my diet.