How long have you been so tired? Have you considered that you might have 'Chronic Fatigue Syndrome' (also known as ME)? Labels like this aren't always helpful but there's a lot of good information to be found about it, if you think you're situation is similar. If you still struggle with symptoms have a look whether it's related to this kind of thing.
A supplement that helps the body to produce energy is D-Ribose. I don't understand the science behind it but it has something to do with the way the mitochondira in cells produce energy. I've found it to be quite helpful. There's an interesting book by Jacob Titelbaum called 'From Fatigued to Fantastic', (parts of it available on Google books for free) which you may want to read.
best wishes in your recovery!