Why do doctors continually administer pain killers instead of treating the problem, knowing the aggressive side affects to pain killers.

It depends.: In general optimal pain treatment would include removing the source of the pain and relieving the need for pain meds. Unfortunately, this is not always possible and pain meds may need to be continually prescribed. There are however many, many pain treatments now available and chronic pain which requires chronic pain meds with aggressive side effects may need to be evaluated by a pain specialist