This is what I think, and you're not going to like it....

When you use Xanax every day, like you do, Mel, your body becomes
habituated to it... used to it.

At 10:30 you were probably starting a mini-withdrawal, your body ready for its dose. Given that you used more muscle power than usual, your level of magnesium was lower too. Those two situations combined to give you a cramp.

Now remember...don't buy the oxide form of magnesium.
Gluconate is ok, citrate ok, ...(I'd avoid aspartate type).

And since you are now on higher lisinopril... you have to watch zinc MORE.
ACE inhibitors deplete zinc and your new dose is high in that regard.
I assume you take a multivit of some kind with zinc in it?