Dull ache at the base of neck on left side under collarbone, throbbing and sore. Causes ?

I have a dull ache at the base of my neck on left side under my collarbone. My neck is sore and it seems to throb about a couple hours after I take my supplements . Today after taking a long walk at the beach and doing push ups it started throbbing more that it ever has. I drank a liter of water and that seemed to help. It first started throbbing at night when I would go to bed and lie on my back. I d have to massage it and roll over for it to go away. Any thoughts on what might be causing this? Could it possibly be related to a tooth problem? Thanks for your help!