Yes to what everyone else said! Please see a speech therapist as soon as you can, one who who specializes in stuttering if you can. Although all speech therapist’s have had at least some training in stuttering (it’s required by the board). The thing is, it’s a low frequency disorder so even if we got training in school we might not actually work with a kid who stutters only every 5 years. I’m 2 years into the field and have only had 1 child who stuttered and it was quite mild. In the mean time, here’s some tips: don’t finish his sentences or thoughts for him, even if you think it’s being helpful, do not rush him or spit it out or anything like that, give him plenty of time to finish his thought, model slow and steady speech, meaning you and your spouse or any other adult can try and be more mindful of the rate you’re speaking with and try to use slower speech. These are the things I learned as an SLP to do with younger children who may grow out of it but I’d love to hear the perspective of people who stutter on these strategies too. If your child is aware of the stutter and shows signs of frustration, I recommend looking up fluency shaping strategies. If he hasn’t yet noticed it, I’d wait to explicitly bring it up until you talk to a speech therapist.