Lower back pain often comes from lacking strength in the abs. You can try to have a few short and simple ab exercises in between to activate your abs. Doesn't need to be anything fancy.
But listen to your body. If the pain gets worse doing it, go to a doctor.
Also, try just to move in between working. Get up regularly and move / walk around around....... reply
the best way to lose fat is either endurance training, for example it is said you start losing fat only after 30 min if jogging, or high intensity interval training, lots of exercises in short time with short breaks.
But it is most important to find an exercise that you like or have fun doing, that will keep you more motivated and will lead to bett...... reply