Lump on Left Shoulder/clavicle

I have been in pain for weeks now.  I have had Arthritis of my neck and spine for many years.  I got up one morning, and felt a terrible pain in the left shoulder.  Later on I noticed a lump which appears to be right on the clavicle in front of my lower neck.  Went for x-rays, and was told there was no disclocation, but bad Arthritis and Tedonitis with lots of calcium depposits.  Would calcium deposits form a lump.  The back of my neck hurts to even move it.  They told me its muscle spasms.  Has anyone dealt with anything with a lump being referred to as Arthritis.