Eureka!

 I found it!  The exact descriptor for the  unusual sensation that has been spordically affecting the outside of my right leg for some weeks now. I mentioned it to my primary care doctor and she said she has the same thing, that painless sensation. I am somewhat dubious. I googled and found it is evidently not rare at all, as manifested by several explanations and descriptions. One source calls it "formication," yes, spelled with an M. Others report those experiencing this creepy-crawly feeling believe that there are bugs beneath their skin.  

  I pretty much put it on the back burner of  my mind and gave up trying to give it a name. Then last night, out of the blue, the precise  term to describe it  suddenly flashed into my mind. The sensation is exactly like that of the motion of a lava lamp.