It sounds like stuttering to me! The muscle tension, the anticipation, etc. It could not be, but to get a better idea I recommend reading “Redefining Stuttering” by John Harrison, someone who stuttered for many years and was part of the National Stuttering Association for many years. You can find a free link to the book if you google the title. If you can’t find it I will help send you a link. I was surprised to find the book for free after seeing it was sold out on Amazon. If this book rings true for you, get back with me and I can send you more resources.