Is it normal to throw up blood while passing a kidney stone? my mom has had kidney stones twice recently and threw up blood.

No not normal: While passing kidney stone possible to have small amount of blood in urine , vomiting blood is serious problem need attention , has to find the cause quickly , you see her doctor for tests and treatment (s)

Passing a stone: Passing a kidney stone often creates nausea and vomiting; blood with emesis is not usual and indicates irritation or even a small "tear" in the stomach mucosa or esophagus mucosa; this is an occurrence that can happen with wretching - severe stimulus to vomit; the wretch can tear the mucosa a bit; the remedy: medication to reduce urge to vomit, like compazine; and a "coating" med like sulcralfate