There are different types of ulcers. Some cause loss of appetite, some cause insatiable hunger. You should check your bowel movements (as horrid as it is). If they are dark, almost black, then you are probably bleeding from your stomach and you should get it checked. Get it checked wither way though, if you are vomiting blood.
It is a common misconception that ulcers are mainly caused by stress or alcohol. This can happen, but there is a bug that causes the symptoms called helocobactor (not sure of the spelling) that can go undetected but cause ulcers and related symptoms when untreated. My uncle recently had a heart attack and is now fine, but the meds he is on revealed a stomach ulcer (caused his stomach to bleed as they aggrevated his ulcer) that he was completely unaware of, being that he does not drink and previously had no symptoms. I htink it will probably transpire that he has had this bug.
Anyway, get it checked and take care.