Margaret,
I understand his and your concerns and hoping all works out in your favor.
Is the spot you mention on his tongue as, "painless, clear, round, raised, hard spot on his mobile tongue", in the center or off to the side? What color is the surface? Does the overlying mucosa or skin look the same as the surronding tongue surface?
If you can answer the above questions I may be able too offer an opinion.
Keep the faith.

Mike