When this happens to me I try something new. The usual stress reduction techniques aren't working so I try a new one until something does work. I also find meditation with deep self analysis helps as I sift out what is contributing to my stress. We often think it should be one big thing that's causing stress. But often it's just a bunch of little things all happening at once that causes tension and stress to mount until it negatively affects stuttering. By effectively removing some of those little stresses it can significantly reduce the cumulative effect of overall stress levels.