I have a dime size lump in back of my head and today at base of my head right side is sore to touch and throbbing a bit and swollen as well. size of r?

Infection? Gland?: Hard to tell and if painful infection needs to be excluded rapidly. Please seek urgent medical attention particularly if fevers/unwell. You will likely need a physical examination.

Could be a boil: Infection of the skin, superficial, that can cause pain that is throbbing and is sore to touch Usually either settles by itself or opens up to let the pus out.

Lump: Possibly, you have folliculitis (inflammation of the hair follicle). Please see your doctor to receive some antibiotics.