Christine, Deb,
I have the same issue as Deb.
My tongue starts to tingle and go numb, and then I start to slur when speaking.
When I check my tongue, either the tip or, recently, just one side turns a gray colour. It looks like meat that's been in the freezer too long. Only about 1cm (1/2 inch) turns gray. Very off-putting.
After about 10 minutes, my tongue starts to hurt quite a lot, for a couple of minutes and then stops.
My tongue will then be it's normal red colour. It's not thrush but does seem to be circulatory in nature.
I only started to notice this on the 2nd January at Heathrow airport in London and it's happened only 6 times.
My doctor had no idea and had never heard of it (he even started calling it blue tongue which is a diasease of cattle!)
I have an appointment with my oncologist on the 21st Jan. Hopefully it's nothing serious.
Richard