Thanks to everyone for their support and well-wishes over the past months with my shoulder pain issues. I now have an answer to what is causing the pain - a bone spur and a 50-70% tear of a tendon (plus some other stuff but I don't understand what)! Now I'm off to the shoulder surgeon to get it fixed up. Hopefully it won't take too long to get in to see them.
Still no reason why - I don't recall a specific incident that sparked the pain, and apparently, often these things are through wear and tear. It seems for me, the minute I turned 40, everything has fallen apart! I'm hoping for a quick and full recovery process so I can get back into stitching more (and my other jobs as well I suppose)...
Have a wonderful weekend!