Suggest Treatment For Bump On The Shoulders

41/68"/220lbs. No thyroid. I had my shoulder repaired (clavicle clipped and torn rotator cuff) about 2 years ago on both shoulders. Left scar has healed nicely but the right side has always seemed a little "angry". This weekend it had a bump, so I squeezed it, and about a half a thimble of blood popped out like a pimple...no pus. Now it scabbed. What is that about?