Help with toadstool...updated pics

[Farrmanchu]

This may sound wierd and risky but, I would take it out, scrape/cut away any part that looks questionable, cut it in half, put the two back in the tank in different places. This should trigger a "fight or flight" response, with one or both of the pieces bouncing back and healing fast. Or, they could both melt away, in any case, it's a do or die way.