Hello, i found a little lump on left side of back of my head, it seems connected to skull, its painless and skin moves freely over it, im so concerned?

Usually is: Lymph nodes are located throughout the body ; generally noticable in exposed areas like the neck. They are usually pea sized at rest and enlarged when stimulated by bug bites, dermatitis, drainage or infection. They rarely can become damaged by infection ; grow to golf ball size ; need drainage or removal. Most enlarge and later shrink back down within a 3 wk cycle unless chronically stimulated.