Hey, I need help. (Newbie)

Hey, I need help. (Newbie) So I'm a male teen and have had relatively normal speaking throughout life. I started talking at an early age. I've always had good grammar and pronunciation. But for some reason, I recently have developed a bad stutter and I have no idea why. I Mostly have problems with vowels, the letters "s" "c" and "p", and have been saying things in a different way. For example, in a conversation today, I was trying to say "cannot", but struggled with the word and said it like this: "can- Canet Can- Cantane-" before finally saying cannot. Y'all probably know the reason, because y'all made a whole subreddit. Please tell me why this is happening.