I have suffered an occurrence of something called Bell's Palsy. Symptoms resemble that of a stroke, drooping mouth, difficulty in speaking, etc. Of course singing is frustrating as all heck.
No treatment. No, just have to wait for it to suddenly go away as suddenly as it arrived.
Good news is I can record the basics, even a crappy vocal for follow purposes, and send them up North to be worked on. However, if this has not gone away by the time I get demo roughs for the real vocals then...
Then I do not know how long it will be before I can sing again.