Why do I have heartburn everyday even when I don't eat? And nausa and black stool abd have upset stomach everyday?

Ulcer. Persistant acid symptoms with black tarry stools and abdominal pain is is danger sign for a bleeding gastric. If you have such symptoms you should seek emergency care immediately.
Need an EGD. All of those symptoms taken together is concerning for a gastric ulcer. Recommend you get your blood count checked immediately and arrange for an upper endoscopy.
Acid Indigestion. Upper abdominal pain associated with heartburn and black stools is a serious condition that can identify benign and malignant causes depending on your age. Please seek a gastroenterologist or surgeon for a thorough exam and endoscopy. Stomach ulcers can progress to rapid hemorrhage and / or perforation. Stomach tumors may behave the same way. Get seen quick.