You didn't say but don't confuse ab exercises with core and back problems. Both your abs and your back are your core, many think only abs are. Then you have your side muscles, latissimus dorsi.

And if you are carrying belly fat, that needs to be gotten rid of because it causes back problems.

Some twisting stretching exercises lying on the floor are a help.

My favorite back exercise is lie face down on a picnic table or a bench with your waist at the edge of the table and feet on the table and your upper body hanging over. Lower yourself and bring yourself back level to the tube. This is a great back stretching exercise.