Six months is a too long time and you should have got evaluated by now. Stomach
diseses, gastritis, peptic ulcer disease, stomach
cancer all can lead to nausea and loss of appetite. Do you also have yellowish discoloration of your skin, eyes and urine? That could be due to gall bladder disease or hepatitis. Eat small healthy meals. You need to consult a primary care physician. He will further refer you to a gastroenterologist.