Yesterday I visited the doctor and he worked to troubleshoot my fatigue/muscle fatigue problems. In taking my history he felt a little test of sensation in my feet might be a good idea, just in case. He expected it to be normal, but it wasn't. I have peripheral neuropathy in my feet - I couldn't feel the microfilament (small soft rubber piece attached to a handle) like I should be able to. Later that night I had my friend Sarah, a neurologist, examine me as well. She tested my temperature sensitivity and sensitivity to vibration, and they are impaired in both my hands and my feet.
The most likely culprit is vitamin B12 deficiency. After that the differential diagnosis gets uglier: type 2 diabetes (unlikely given my weight, exercise, etc., but still possible), some kind of de-myelinating disorder, and the list goes on. But as my husband pointed out, "Common things are common", meaning that usually the most common thing is the problem. B12 deficiency is very common, which is probably why my doc thought of testing my peripheral nerves - B12 deficiency is known to cause both fatigue and peripheral neuropathy.
They drew blood and are checking B12 levels along with serum ferritin, thyroid, CBC, and probably some other stuff too. They'll have the results to me in a day or two. Meanwhile, I am a bit concerned but trying not to worry, as it's not like that will accomplish anything. At the same time, I am slightly relieved that something really is wrong, as it makes sense of a lot of things and explains why I have been feeling so "off".
This morning my glutes and hamstrings were sore, and I was mentally too tired to racewalk, so I opted for the elliptical for 45 min followed by riding my bike to work.
I think I'll take a nap after work today if I can squeeze it in... (I work 30 hr/wk so can leave mid-afternoon).