How rare would it be for a 19 year old to have pancreatic cancer? ive had constant upper abdominal fullness/tightness for a week now, as well as a curbed appetite, and skin itchiness. the abdominal discomfort has gradually intensified and im scared?

Extremely rare. However ranging from trying to self diagnose using Internet to seeing your doc for advise, self diagnosis will only negatively influence you by exacerbating anxiety and leaving symptoms untreated, while seeing your doc will help both mentally providing peace of mind and physically as soon as a clear diagnosis formulated and until then by treating your symptoms.

Very rare. It is not feasible to provide an opinion without additional history, physical examination may be some tests. It would be prudent to see your doctor to see if you may be depressed. Depression is treatable. Counter-intuitive as it may seem, exercise may help. Start with low intensity exercise such as walking and gradually increase the intensity as tolerated. Drink more water.