It's not common but not unheard to have have very late developmental stuttering (not sure if you peuld even call it developmental at that point). The honest to goodness best advice I can give is to take it in stride and not fight it. Fighting it, being afraid to stutter, staying silent, all this makes everything 10x worse. What you need to focus on is how to be yourself and do what you did before, just with a stutter. I recommend finding a speech therapist who knows how to help in this regard. If you find one who says they can teach you to control it, I think you're gonna have a bad time.