A relapse is simply a mindset you fall into. You know you can speak fine already right? There's just some type of doubt and tension getting into the way now. I have found that a big reason stuttering can come back is by feeling a big sense of uncertainty in your life. This uncertainty created a lot of tension in the body. Has anything recently changed in your life? Habits, environments, people, weather, etc. Most people who stutter are HSP's (highly sensitive people) around 80%.. so small changes can trigger emotional states to arise which if not dealt with correctly can make yous store tension in the body