Hi Newman, I'm another who thinks the problem is in the blood.
When I have a large blood test, all my extreme fatigue symptoms disapear for about four days. It's not just a little improvement either, it's amazing. My doctor was skeptical, so I donated a full 470ml of blood, and my fatigue symptoms disappeared for four weeks!
I also have always felt better during menstruation, and my symptoms seem to follow my hormonal cycles.
My neurologist thinks it's MS, my rheumatologist and dermatologist think I have Porphyria. I developed my brain lesion and corresponding loss of right hand movement in 2008. At the time my ferritin levels were above normal and my transferrin was highly iron saturated.
I wish some doctor would just test what the hell happens to me when I loose blood because I feel so good, like I'm 20 again. The more blood taken the longer the effect lasts.
I also feel much more energetic when I take aspirin daily, but get stomach problems after about three weeks, so I can't do it regularly.
Lupus and Porphyria have a link somewhere from memory.
Porphyria is a genetic/acquired disfunction in heme synthesis, often exacerbated by environmental triggers.