Lots of COPD patients suffer back pain, muscle spasms. Our diaphragm is working so hard to get us air and causes overextended muscle, ligaments and sometimes bone pain. My doctor put me on Gabapentin and it helps tremendously. I also take an antianxiety pill but not very often. Muscle relaxers help and I also bought a TENS unit that helps.
Discuss options with your doctor. I know, easier said than done. Sometimes they just don't listen. Keep us posted

Possibly. Usually the pain is higher, and from the shoulder and mid chest muscles, but it could be lower. Muscle pain is usually easy to identify. It would be more generally located; not in one place. If you have lower back pain in the middle, that may be something else. It's worth getting checked out, because back pain can be indicative of so many things.

I agree with jeans comments. I would suggest you go have it checked out just in case. Good luck to you blessings are sent your way.