Last year I noticed a hard lump at the base of the back of my neck. After a few weeks I went to the doctors and they said likely a muscle knot, I had a blood test which was fine. One year later and the hard, immovable, painless lump is still there. I have googled muscle knots which say it would cause a dull pain however this is painless. Should I go back to the doctors and ask for more tests?