One can develop allergies or the like at any age. You aren't going to go through life without an illness or without troubles. However, stuttering is a speech disability and you learn to manage it. If you think this is anxiety related, wouldn't your post serve better on a mental health subreddit? Or better yet, seek counseling and medication for an anxiety disorder. There's no shame in it. Just google how many people in this world medicate themselves for depression or anxiety. Most of us here understand that stuttering is neurological challenge like a tic disorder. Don't confuse the two.