Fatigue, Dizziness, Nausea And Malaise. Blood Test Shows Low Iron, Other Tests Normal. Possible Cause ?

Hi, I am a 27yr old Female. For the past year I have been experiencing symptoms of fatigue , dizziness , sometimes nausea and malaise . I ignored it on advice of my doctor putting it down to stress etc. My initial blood tests showed low iron, low vit D. I left the doctor with supplements . I have noticed though the last 3 months or so that the malaise is more consistent (it used to happen every now and then), I also wake up sometimes feeling like I ve been run over by a train- sore bones, muscles (without any apparent reason) as well as swelling in my ankles (fluid retention) pain in my right hand side back area near ribs with swelling there as well. I have had several blood tests, renal scan, abdomen scan, CT of brain, heart scan with no indication of what the problem might be. My bloods are showing low iron, low Vit d and high albumin. I take my vitamins daily. Thyroid and other tests ok. Could you please help me? I am sick of feeling this way, and have tried just about everything. I have always eaten healthily, don t smoke and drink rarely. I do yoga every week as well as walking. I have put on 5-10 kg in the past 6 months where my usual weight is around 55-60kg.