New snake owner with vomiting 4 month old

I bought Persephone 3 weeks ago at a pet store and it seemed like she was doing pretty well, she had no problem eating frozen pinkies and seems to be gaining confidence in her enclosure. But after feeding her on thursday evening, I woke up on sunday to find what I think is vomit. I have never owned a snake before and I would really appreciate some advice, my preferred vet clinic is closed on sunday and I don't know if how serious something like this is.

It's a weird color, but given how 'entraily' it looks, I suspect it's actually a poop. And just to clarify - when you say you're feeding her frozen pinkies, you do mean that they're thawed prior to feeding, right? Do you have any reason to believe it's a regurge? Things like stress after feeding (like being handled or something bumping her enclosure), improper temps, mouse was rotten, meal too large? Anything like that? If you haven't thrown the suspected regurge away yet, take a toothpick and pick it apart to see if you can find any identifiable mouse parts (like a face or a leg or whatever). Also, if it has urates with it (the white powdery stuff), you know it came out the back end.

I am beginning to suspect it is poop as well, so far her poop has been small and black with urates so this big horrible looking thing vaught me off guard and I think I overreacted. I put the pinky in a small bag which I thaw in a bowl of warm water. I feed her in her enclosure on a tubberware lid to avoid her ingesting substrate, but this time she grabbed the food from the tongs before I set it in place and I was worried she ingested some aspen. This is my first snake and she is already my baby, so I think I might just be being an overprotective parent. Thank you for the quick response and advice.