First of all you need to figure out what type of stuttering you have. There is flight, fight and freeze. !The type you have can change over the years!. Look up information about the types. Then look at the way you breathe. Do you breathe before every sentence? Or exhale mid-sentence? Also figure out the letter you stutter, is it in the middle of a word? At the start? Do this first so you are prepared when going to a specialist. Punching yourself however is in no way right. You focus your energy on other parts of your body instead of your mouth so speaking will become easier, this is however just avoiding the problem. I could help you with basics a bit but im not that good.