Hello!
Thank you for the query.
There can be plenty of reasons for vomiting in the morning. The most common are due to stomach diseases like
peptic ulcer, stomach mucosa inflammation,
stomach cancer, gallstones, bowel obstruction, vertigo (caused by brain diseases or internal ear diseases), diabetes and many more.
If your dad is having also
abdominal pain it can be peptic ulcer (the pain is in the upper middle abdomen) or gallstones (pain in the right upper abdomen radiating to the back). If he has also lost some weight recently cancer is possible. If he has any dizziness or headaches, brain problems are possible.
Depending of the additional symptoms, proper diagnostics is advisable(upper GI endoscopy, abdominal
ultrasound, full blood work, liver tests, pancreas tests,
colonoscopy, head CT, blood sugar level, etc).
Hope this will help.
Regards.