Welcome @allyjane61, You've been through so much! Hopefully you will remain cancer free now. As frouke noted, this type of ongoing pain can happen. It's unfortunate that with everything else that you've dealt with, you still have this persistent pain. Hopefully the massage therapist and/or gabapentin is able to offer some relief.
Here's a search for other similar discussions, which at the very least shows that you are not alone:
https://connect.mayoclinic.org/group/lung-cancer/