I went through this late last year. It was very work/stress/mood related and it was a hard 4-5 months (my stutter reached the worst it's been in over 10 years). Basically the only thing I could find that helped was to make efforts to make myself happier. I know that's much easier said than done but it's how it worked for me. Basically, when I worked on/fixed the issues in my life, my stutter improved. Best of luck, I know how hard and frustrating it is.