I've never had anything like this happen to me, and i'm sure there will be more experienced replies to follow. How big is your snake and how big was the mouse you fed her? (i'm assuming you bought her as a hatchling) if it was too big im thinking she will regurge, but like I said i'm no expert. If shes been trying to eat that mouse for 4 hours it was probably way to big. If you mean "small" as by what pet stores market it as, its probably too big at that age, but I don't know because there's no weight or age or pictures.
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