The throbbing that you mentioned is it visible or are you feeling it on your finger? The slight throb that you feel between the collar bone is a pulse. The lateral side of the neck i.e the side of the neck throb felt is the pulse of a vein (jugular vein
). The neck pulse is a strong pulse which can be easily felt. Did you get up because of the throbbing ? Generally the pulse at the neck is not visible, but sometimes it because of some pathology such as high blood pressure
Few questions that are important , are you a diabetic / hypertensive ?
I suggest that if this is visible for the next few days do check with your family physician to rule out any pathology.
Do get back for any further queries.