My Little Sister Drunk Bleach , I'm Not Sure How

My little sister drunk bleach , I'm not sure how much . I think just a sip , she's three years old and I don't know what to do . She started throwing up and coughing alot . She did it about ten minutes ago and she looks fine now but I'm worried because she refuses to eat or drink because she says it hurts . what can I do without bringing her to a hospital ? And why does it hurt her ?