I believe we can spasm anywhere.

My worst spasms are when I take a drug that I am sensitive to, such
as the various extras in flu shots, like mercury and adjuvants (things
added which are somewhat toxic and aid the working of the main
ingredient.) My worst clenchies are my jaws and hands, but my
back gets rigid along the spine, both or either side. Feet can even
spasm, although calcium and magnesium helps.

I too have that odd spasmy thing when I stand up after getting up
from bed, have to do it in stages and deliberately relax parts of
legs and back to stretch to full height.

I don't think I've had the type of spasm you describe but I believe I
could have a spasm anywhere, including the gut.

And that's what I think a clenchy is. When I was at my worst, just before
dx of MS, my hands were almost always clenched. Maybe that was partly
nervous tensions, extreme distress trying to find out what was the matter.
Getting off Meprobamate and onto Klonopin at that time helped very much
with that.

Hoping you unclench for Christmas and can enjoy the lights and sounds.

Mariel