In migraines i make myself vomit to feel better,but after every vomit i spit up blood in saliva.which is fine after 10 mins.vomits r often forceful.

OK, but not repeated: It's very common for people to have some bleeding after vomiting forcefully. The esophagus is irritated and bleeds. Fortunately, it is a constrictor muscle, so it stops its own bleeding. For this to happen once or twice is not harmful. However, constant irritation of the esophagus can lead to other health problems, so it is not something you want to happen frequently.