This is one of those times when I wish our virtual community was a little closer physically! Glad your parents are there for you, Teresa. :) And love the way you helped minimize Jack's fears for Mum with the radioactivity story! :D
My mother used to have occasional bouts with something called pleurisy--symptoms similar to yours. Had to look it up on Wikipedia to see what it actually is--all I could remember was the pain and shortness of breath. Now that I'm thinking about it, it seems to be related to when she had periods of enforced inactivity--surgery, injury, etc.
I couldn't get the link to work, but the path is below. I just read the basic description and certainly wouldn't consider any information to be a comprehensive or absolutely accurate source of medical information, but it might be a possibility if the doctors rule everything else out and the pain persists.
I have the feeling that it's one of those things modern doctors often don't think about.
What ever is causing your pain, I hope it ceases and desists soon and you feel better!
Edited to add:
Wouldn't you know? The link finally decided to work!