Try some low-dose anti-anxiety medications like Clonipin, Ativan. It may not work for everyone but I started those meds 20 years ago and it definitely made a difference in my fluency. I'd say 50% increase. I'm certainly not pushing drugs for stuttering but it can't hurt to try IMO. They really helped me and my quality of life. Also, you are a kind soul for caring about your brother so much. I wish I had someone similar when I was in his position. What a great brother you are, sir.