I have had this problem before, and to get your back feeling better is quite simple but takes patience. Lay on your back with your legs in the air. Keep your knees at a 90 degree angle, and go side to side slowly. DO NOT LET YOUR LEGS HIT THE GROUND! After a few reps of this, lay with your legs to one side. Put your outside leg over your inside, and let it rest on it. You should feel a good stretch on the muscles in your back. Repeat on the other side. Then role back and forth with your legs straight up (Like your doing a backwards summersault except dont). After that, lay on your back again and turn your torso and legs in opposite directions. This should pop your lower back.
Hope it helps