is my stuttering caused by cognitive problem ?

is my stuttering caused by cognitive problem ? i have noticed i stutter alot ,have persistent fatigue and tiredness despite my cbc tes & thyroid tests & fasting blood sugar &liver & kidney functions & cortisol test ,having a long sentence is not as easy when iam tired i don't know what is wrong me ,i went to a neurologist he asked me to my arms and then said nothing wrong with you,what is the correct step address this issue.