People stutter for a variety of reasons. Over the last year i've really focused on my stuttering patterns, what may have caused an increase in my stutter, food, water, sleep, exercise, anxiety etc I suggest you do the same, if you notice that one day, or a specific period of time you've stuttered more than usual, note down your mood, environment etc and narrow it down. I personally stutter when I have bad sleep, little water intake or when my social anxiety kicks in.