Lower right back pain when hungry and goes away after i eat. is it just from hunger?

No: This is concerning for a peptic (stomach) or duodenal (small intestine) ulceration or cholecystitis (inflammation of the gall bladder). Eating decreases the acidity of the contents of the stomach and intestine and will decrease pain. It also makes the gall bladder contract so eating usually increases gall bladder pain. See your primary or a gastroenterologist.