Working in a call center with a stutter is insanely commandable. Nightmare fuel for most stutterers to say the least. I'd assume you were affected by one of the calls. Have you had existential thoughts lately? Something bothering you? Anyway not to get too personal, if you haven't tried I'd suggest therapy (CBT helped me, but it depends on the therapist) or at the minimum try taking a moment to sit by yourself in silence and see what comes up.