The same thing has happened to me twice in my life so far. The first time was at the beginning of 8th grade. I was very fluent and sociable in the previous grades, but in 8th grade a lot of my schoolmates became pretty mean, which resulted in me becoming self conscious, closing myself off, and then getting a severe stutter. This passed about halfway through Freshman year, though, when this new kid went out of his way to make friends with me, and my French teacher really pushed me to start speaking more. The second period was at the beginning of 10th grade, when I tried weed for the first time. It made me really anxious and triggered my stuttering, which stayed even after I came off the high. I stopped smoking, but this period never really ended. It got worse a few months later (during COVID), and has been gradually getting better since. Still hoping I get another fluent period sometime soon!