Well, black might be overstating it, but gray/black and only (so far) on the right upper portion. Just noticed it last night when brushing his teeth. Eight days into rad tx. He's not up yet this a.m. but I see he was up middle of the night as there's the bottle of Compazine, Pepto-Bismol, crackers, water, and a book here downstairs. I typed in "black tongue" under "Search" but didn't see anything regarding this weird-looking condition (which he only noticed b/c he was checking his oral cavity w/a light last night, not b/c it hurt or anything. Anyone else have this? Is it likely fungus (without the fun)?