Since a fluid golf swing requires flexibility and good rotation, having tight hip flexors can detract from the power of your swing.  Tight hips can also contribute to lower back pain and can cause players to overuse their arms, injuring their wrists.  My personal trainer suggested that I routinely stretch my hip flexors to help protect my back and other parts of my body.  I recommend sticking with a training program that not only helps you maintain strength, but also flexibility which is especially important for seniors.  Hopefully this would also help reduce the pain you are experiencing!