When I touch a spot on the lower part of my neck above my collarbone, I feel a strange vibration that's very noticable. It's not my heartbeat. What could it be?
A thrill. This vibration is called a "thrill" and usually indicates a connection, or fistula, between an artery and a vein. There are many arteries and veins in the region you describe. See your doctor- this is not a normal finding and should be diagnosed.
Bruit. Need to be checked for carotid or subclavian artery stenosis.