At 65 now i've suffered back and shoulder issues over the years. Last 4 yrs going to gym has definitely helped but you need to find out what exercises will help your issue. The gym Personal Trainers have all been very helpful in the small family run gym i use. Weight training in past 6mths has been a godsend for me. Not rapid movements but slow controlled weight lifting with 3 second negatives.
I still won't use a 10lb plus bass for a full gig but prefer my Sandbergs which are a good easy weight around the 8.5 lbs.
Pretty sure i've had this conversation with @Lozz196 before and he's been down the fitness route too but obviously not resolved his own back issue.
Dave