Welcome to HCM,
His case requires evaluation as passing blood in vomitus is not normal.
It is possible that he might have acute gastritis
or gastric ulcer or Oesophageal varices
Go for ultra sound
of upper abdomen and find out the source of bleeding.
Quit alcohol or smoking if he has these habits.
Give milk and liquid diet
If bleeding is severe then consult Gastro enterologist.
Ok and bye.