Hopefully it's nothing. The hardened patches may be almost like a callous - possibly built up from irritation over a long time. What kind of cream did she prescribe? I have this awesome cortisone cream I use on rare occasions when my tongue is irritated. Radiation of course caused it to be super sensitive. And it's a little big for my mouth because of the graft so I occasionally bite it by accident All this combined with eating irritating foods and I sometimes need this cream for a spot treatment for a day or two. It heals everything right up.

If what you have doesn't heal. Get a second opinion. A good dr. is not put off by a second opinion.
take care