left shoulder/collarbone pain

Hi! This doesn’t occur every time I run, but it happens often enough to ask. In the first two miles of a run of any length, my left shoulder/collarbone will get this ache that ranges from dull to a sharp jab feeling. Most of the time it works itself out throughout the duration of my run. Is this something to do with posture?

This also happened when I was younger and dancing quite frequently, but I ignored it then (lol).

Thank you!