Whirlwind,
I agree with Annie that it sounds like a pinched nerve and is not MG related. I have had that in the past and have times where I get this catch like feeling in between my shoulder blades. I have also had the pins and needles feeling from it. I notice that mine gets worse when I go to bed and lay on my side. For some reason that really puts pressure on it until I adjust and I get comfortable.
I have a fabulous chiropractor who can fix that when it happens to me. If you are open to chiropractic you might look for a good one and give it a try. If you don't currently have a chiropractor ask around for someone who can recommend a good one. They are the same as any other practice, some are MUCH better than others.
Kendra