You should see a doctor immediately if you are experiencing blood in the vomit. You may be experiencing the symptoms of a bleeding ULCER or another serious condition such as CANCER. Other possible causes of vomitting blood including ingested blood (swallow blooding during a nosebleed, for example), prolonged or vigorous vomiting and/or internal inflammation. Vomiting red blood indicates that bleeding began just before you vomited. If the blood is black or appears dark brown and has the texture of old coffee grounds, the blood has been in your stomach for a longer time.