I am also wondering if this could be sand impaction.
They are in a sand tank, and some might have been ingested.
Thus, maybe epsom salts could help,
as she's not eating, and peas are impossible.

How could I know if there is a bacterial element to this?
There is no redness, or anything like that.

If she does pass whatever is blocking her,
I'll check to see if it's sandy at all.

Or, if god forbid she passes on,
I'll do a necropsy to be sure it wasn't sand impaction.
If that's the case, I'm changing substrate.