It's been almost 4 years since I've had SGBs but from what I remember, if you get some relief it's a good indication. I never read anything that said blocks caused spreading but then again, it was years ago that I did research on the subject. I had 10 blocks within 3 or 4 weeks.
I don't know if they ultimately helped or not but I got some great short term relief on some of them. I hope they help you.
Linmarie