You probably had a distal clavicle excision where they grind off the end of the collar bone to give more room to the AC joint where the collar bone meets the shoulder blade on top of your shoulder. You can get very bad osteoarthritis there. I've had both done.
It takes about 3-4 months for the pain to go. It's like having a broken bone heal except it needs to grow new cartilage on the end and that takes more time.
But once it's fixed, it feels great!
gentle hugs.............Jenny