Is my caterpillar dying?

Good morning.

I'm currently breeding swallowtail caterpillars. (I'll release them into the wild as butterflies, of course). When I got home today, I saw that a caterpillar in its cage had fallen from the plant onto the ground. (I have very small stones covering the ground.) One of the stones was extremely moist, and I saw that the caterpillar was vomiting up a yellow fluid. I googled it and found out that they do this shortly before pupation… I don't know if it's the same with her.

I have the feeling she doesn't have the strength to hold on to anything right now, or only to a limited extent. She's also twitching a lot, and when I touch her (very lightly with a parsley leaf or something soft), she doesn't react the same way as the others… I mean, for example, that she's becoming active or perhaps flexing her antennae in defense. As I said, I'm being very cautious about that.

I built something out of tissues and toothpicks so she can lie at an angle (with her head up) without using much force, in the hope that she will pupate… She won't get squashed in there, and it's soft, too.

I can imagine that it fell off while being tied up during the pupation phase.

But I can also imagine that she suffered a serious fall…

Maybe someone has had similar experiences and can give me tips… It would be a real shame if the caterpillar died 🥺

And the others of their size (I think that's the last phase before pupation anyway) are still eating normally and carrying on as normal….

Does anyone have any ideas? Does anyone know if she's dying or just twitching to shed her skin or pupate?

Would really appreciate help