Why do I continue having back pain

Patient: I have had a pain in my lower back to the left and right hand side its is mosyly there if im sitting up straight in a seat or carrying a bag. I can be pain free untill I carry something in one of my hands. I have had this for about a year with no help from my doctor he just says its because im slightly over weight.

Symptoms: Pain in both sides of my back with the pain feeling as if it hoes threw yo my stomach