I'm still a member, still sole admin, have posted nothing breaking the rules. I can like a post or comment, but Facebook will not allow me to make a post or comment (including on a post that I made). I have refreshed the page (multiple times), and logged out & back on.
I can still post and comment on my personal page and on my biz page, but not in the group that I run. I reported the problem to Facebook and got an automated answer.