Werid lump on my shoulder/collarbone area?

I have this strange lump on my collar bone, its not the first i've gotten. I usually get them on either my collar bone or shoulder and its always on my right side. They are not extremely large but they're not pimples. It will start out by hurting to the touch and then spread to hurt at the movement of my shoulder, then neck, and then it just hurts everywhere all the time. They will usually go away after a week or so but then reappear shortly after. Can anyone tell me what these are and if i should be worried?