Pain by collarbone

I had a TT and right-side neck dissection 5 weeks ago, but about 2 weeks ago (3 weeks post-surgery), I started feeling pain around my collarbone on the left side (opposite side of the neck dissection). It hasn’t gone away, and if anything has gotten worse. The pain has started extending to my upper chest too. Have any of you experienced something like this?

And is this something I should reach out to my primary care doctor about (or my endocrinologist, or my surgeon)? If I don’t know what’s causing it, who am I supposed to go to about it?