I get the same thing I'll go through days or weeks of more severe stuttering. To the point where friends around me will ask me if I'm OK because I've been stuttering more than usual. The best thing I find that helps bring me back to my normal level and stay there is just taking a little time each day to I guess you'd call it meditate but just go lay down some where by yourself and just close you eyes and try to relax even for just ten or 15 minutes.. It's not always easy to do but it just brings down my dayly anxiety. I feel like it's an accumulative effect. The more I do it the more it helps.