Mine is the same. Something in universe changes, I don’t know what, and I start to stutter and struggle to be fluent. It usually lasts a few weeks, and then slowly dissipates and I am literally spontaneously fluent for months, then suddenly, rinse and repeat. The worst part is it’s unpredictable, and I can never build any good coping skills or acceptance mechanisms. As soon as I stop panicking and start to try to cope, I become fluent. And then when I least expect it, it comes back. I have never been a severe or profound stutterer but I have had moderate flares and they suck.