For the past year, I've had a golfball sized lump deep under the skin between left clavicle and top of shoulder/neck. It appeared after waking up one day with immense neck pain and flu like systems. Doctor determined it was tonsillitis and didn't seem too worries about the lump, even though it was hard and only slightly painful to the touch. The lump stayed, though, and had been worrying me. Now, I just noticed the lump seems to be gone. What could it have been? and is it still there but moved/can't find it?