Suggest Treatment For Hard Lumps On The Skull

During the last week a number of hard lumps have appeared on my skull. . They are hard and do not move under the skin. The lumps are neither sore nor painful. However, the area from the lumps down the left side of my skull behind the ear is quite sore - even painful. The soreness seems to be on the surface - in the bone- and reaches down to the bottom of the skull behind the ear. I feel as it is affecting my stomach. What should I do? MB