To bounce off this, (and I’ll preface this by saying I’m in school to be a speech therapist, so I’m not a licensed therapist yet), you’re right! And OP is not a freak. What he’s describing are clinically categorized as secondary characteristics to a stutter - very typical for someone who stutters to have other body movements when they “can’t get a word out”. I’ve seen children, adolescents, and adults that exhibit the behavior that he describes as “seizure”-like - you’re not alone!