Dear Cassie, Driving trucks for long hours is a risk factor for faster degeneration of lumbar spine
(lower back). However, at the age of 60, with history of smoking, loss of appetite, and recent weight loss
(if any) strongly point to the need for investigation of the low back pain
by clinical evaluation and some basic investigations to rule out the presence of any serious disease (need to think of tumor/ osteoporotic fracture/ infection).
It would be wise to take him to an Orthopaedic /Spine surgeon