Did you try the ultra pure Ajipure glycine? That is more expensive, but many have no problem with it, versus normal glycine powders:
Thanks for the suggestion; I’ll look into it
Coincidentally, just this morning, with the help of AI, I found a treatment for the spasm. I am desperate for something that can be administer acutely because the attack is 12 hours of living hell. It is nitroglycerin, administered sublingually, same as for heart pain (smooth muscle). Lord, I wish I would have known about that earlier.