There are different types of stuttering and they can exhibit differently. There is developmental stuttering which involves repeating sounds, prolonged sounds and blocking sounds. There is neurogenic stuttering (usually caused by stroke or brain injury, tumor etc.) and this type may involve stuttering in the middle of a word not always at the beginning. There is psychogenic stuttering (can be caused by trauma, stress, anxiety). There might be a few other sub types I don't know about. Not exactly sure what you mean by "all in your head," because if the etiology of something is based on emotional or psychological issues, it may not have a physical cause, that doesn't mean it doesn't exist. It also doesn't mean there isn't a genetic component, but the combination of hereditary factors and environmental factors are difficult to separate. You're right that the treatment can be different for different types of stuttering. Psychotherapy would help for psychogenic stuttering because the basis is emotional and psychological issues. (It wouldn't help with neurogenic stuttering which is based in brain trauma.) Not a psychiatrist (a doctor who prescribes psychiatric medication) but a psycho*therapist* would be the best option I would say. I don't think that developmental stuttering is a speech language pathology issue so speech therapy probably wouldn't be helpful for that either. It's not the same thing as a lisp or other issues involving the way the mouth pronounces phonemes. It is more psychologically based so yeah speech therapy isn't usually used as a treatment.