I just made a little discovery for my stutter

I just made a little discovery for my stutter I've always had a problem with three specific sounds when speaking, in addition to my regular, not very severe stutter. The m, p and especially b sounds have always been a burden. I completely block out when a sentence I start starts with one of those three. I very rarely order a Big Mac at McDonald's because I'll have to stay there, dumbfounded and embarrassed in front of the poor employee that probably thinks I've gone mute for several seconds before a sound comes out. And it's usually so surprising to me when I produce the sound, that I stop talking and have to start again... and then I order a cheeseburger, because "ch" is a lovely and easy sound for me. I noticed something however the last time I wore a tight shirt around my neck. When I produce any of those sounds my whole neck stiffens up and I put so much effort into saying them, while with others it's not at all so. When I searched for mouth positions for the sound b, which is the most problematic one, I found [this](http://profspevack.com/archive/animation/tech_support/images/lipsync_guide.jpg) chart. Essentially, all three sounds start off with the same mouth position, and I put incredible amounts of energy to even fo from the starting position to the next sound. My hope now is that the problem with those three is purely mechanical, which can be hopefully solved with exercise and training in front of the mirror. Does anyone else have a problem with a particular group of sounds and how have you tried to solve it?