Hello! Welcome to HealthcareMagic! Fatigue, headache, dizziness are due to your low hemoglobin levels. A good diet intake is more important. Rest from work would also help you concentrate on your self. As due to work load we tend to neglect health at times. I would advice you to continue taking ferrous sulphate till hemoglobin has increased. Can easily tell this without a lab test. You will notice your stools become black and hard in consistency, that is when your iron stores in body have been replenished and do not need to uptake anymore iron hence the black hard stools. I would also generally advice patients to eat a fibrous diet while on ferrous sulphate, as the hard stools might be difficult to pass if a good diet intake isn t maintained. Hope that clarifies your concern. Thank you for the query. Take care Regards, Dr. Vignan Rachabattuni, General & Family Physician