I have been naususe for several months, now the past 2 days I have been having black stools I mean coal black what's wrong?

Time to see your doc. The signs and symptoms your are describing could be related to an ulcer. Time to see your doctor for a check up.
Melena. If you have black, tarry, malodorous stool - it is very possibe that you have gastrointestinal bleeding. If that is the case get this assessed asap. If you are taking a medication like pepto bismal for your abdominal discomfort- it may be turning the stool black.