Hallo,

So the colouring is caused by a trapped
nerve, which could be caused by a cyst or tumor, which could originate
from internal bacterial infections (acccording the website).

Or an infection of the nerve directly.

Interesting that the
colouring almost disappeared again, maybe it recovered, and then had a
fatal setback.

Maybe. Or the position of the cyst (or something else) has changed.


--
Grüße
Norbert (Heidbüchel)