What Causes Tiredness Along With Mood Swings?

Hi, I am a 29yr old female, I have been tired even after an 8hr sleep then I will get up an make food 2 hrs later I am so tired usually 4 hrs am I start to get nauseated an hungry an really irritable an grumpy, I start to shake an feel like I m about to pass out, if I eat food that makes the weak, grumpy an shakiness go away but I m still so tired. My dizzy spells are quite frequent but irregular usually total loss of vision for approx 5 seconds but today I only lost sight in my right eye. My bp usually sits around 109/73 an pulse 78 my blood sugars are usually around 4.5 mmol an I m mildly anaemic, my thyroid, adrenals, colesterol, hormones an fasting glucose are all apparently normal, my STD/SDI tests all came back negative, I have not been under large amounts of stress or long hours, I have coeliac disease any suggestions?