Hello Nasar. The cause of your anemia - low hemoglobin appears to be iron deficiency as hemoglobin improves when you take iron tablets. The cause of iron deficiency can be low intake of iron in your food as also increased blood loss leading to loss of iron. As you have heartburn and problems after taking food, an ulcer and blood loss due to that needs to be ruled out. That can be found out by doing a stool examination and can be confirmed by endoscopy. The problem, though not serious and easily curable, needs to be attended by a good doctor and tackled immediately so that it does not become bigger! Trust I have answered your question.