Neck Spasm/ strained blood vessel?

I wasn't doing anything strenuous when all of a sudden I had a "charlie horse" or a spasm in my neck. I reached to feel the area and noticed a lump that I did not have prior to the spasm. The spasm came and went, only lasting for about 5 seconds. After examining it in the mirror, it appeared to be a blood vessel that was protruding, in the right area of my neck above my collar bone. I went to my physician immediately and they diagnosed it as a strained blood vessel in my neck and prescribed a pain killer and a muscle relaxer. Its only been a day but my neck is very tight feeling and the area is very painful to the touch. The doctor said the pain will reside on its own, and the swelling may go down, but the appearance of the lump (vein) may not go away. The day before I had lifted a laser printer that was about 10 lbs or less, but I did not feel like I was straining anything, or that it was heavy enough to cause an injury. I also thought it strange that out of nowhere the spasm occurred and in result I have a bulging vein protruding from my neck, but the doctor insists its nothing to worry about unless it gets worse. Has anyone had this happen or know of this happening to someone else it just seems uncommon to me...