Had an fbc last week and my iron came back at 6.2. it's not normally low and haven't changed my diet recently. the doc said i need supplements. should i be worried? haemoglobin 12.8.

Periods: The most common cause of low iron in women you age is menstrual blood loss. You may not be taking in enough iron to compensate other possibilities are blood loss from your gastrointestinal tract (less likely at you age) or a malabsorption problem like celiac disease ( gluten intolerance) . Nexium (esomeprazole) could affect absorption. Black stool can mean upper GI tract bleeding although iron do this.

Ferritin: You're losing blood from somewhere .In young ladies it could be from heavy menstruation but if not you might have to have a workup including endoscopy and colonoscopy to check for any bleeding sites.