There are several reasons you may see blood in your vomit.
-You may have a tear in the lining of your stomach, or in your throat. -You could have an bleeding ulcer. -Heartburn can cause bleeding inside the esophagus if persistent heartburn has caused ulcers to form in the esophagus. -You may be mistaking the red substance in your vomit for blood. It may just be something you ate, that is red. -It could be ruptured veins in your throat from vomiting.
No one here can tell you exactly what is wrong, but anytime you have blood in your vomit, you need to see a doctor or go to the emergency room...It could be serious.
It can mean a lot of things. Bleeding Ulcer is the first thing that comes to mind for me. In any case if this is happening to you go to the ER ASAP.
it means you get your arse to A&E if your GP is closed
That you are ill, go see a doctor
go to the doctor !!