As Hypoguy mentioned, about hypoglycemia, during one of my naturopath visits years ago for a yeast detox, there was a woman in the office who was also weak and had many of the symptoms you described, extreme fatigue as well to the point she could barely sit up in the chair in the office waiting room.
Have you had a live blood culture test done? Difference from a regular blood test, pin prink, blood is then placed under a high resolution microscope and video taped. Count is down of white blood cells, microbes (yeast), RBC, all the cells are looked at right there with you and discussed/explained. Cells are not centrifuged and separated as in a regular blood test (by which time they're all dead from lack of oxygen, etc)
In my case I had 5x the regular amount of microbes in my blood count....6 weeks of yeast detox for me. It may be the microbes depriving you of all nutrients in your blood/system and wrecking havoc in your body elsewhere. My regular Dr.told me at the time there was nothing wrong with me and that I was likely overexerting myself. WhateVer.