Does she take aspirin or ibuprofen? Is she an over-eater or an under-eater? Aspirin, ibuprofen, alchohol are very hard on the lining of the esophagus and stomach. More so if there is not enough food to absorb it.
If someone is vomiting blood, they need to be seen by a doctor. Vomiting repeatedly an cause broken blood vessels and it needs to be checked out by a doctor.
Vomiting blood is a symptom that could be simple, nothing to worry about. Or it could be a sign of something more serious, but can be treated. If she has been vomiting blood, this is something that should be addressed at Urgent Care or a hospital's Emergency Department. They will do the necessary scans, scopes and whatever is needed. The good news is you will likely find out why she was vomiting blood, and they will tell you who she needs to see, and what she needs to do to..