Hey JMC, could you resolve this problem? I have similar issues and am also not considered to have muscle disease (thoguh never had a biopsy). However, i feel this abnormality in all my muscles. Whatever I do, using a screwdriver, standing too long, respective musles start hurting. With rest, pain goes away very quickly (although time is proportional to degree of exertion). Comes back quickly when I continue. I thought of mitochondriopathy finally but a university hospital neurologist said that this was extremely unlikely from what I described and without specific signs and normal EMG etc.
In the past (not now anymore) I felt better during vacation but consider it unlikely that this comes from distress etc. alone. Also thought of vit D insufficiency but values were not extremely low.
I not a medical professional or in the medical field; However, I had similar pain for years...I went to numerous doctors, orthopedic and nurosurgeons, none knew what it was. Finally, afetr much research I decided to try a vein specialist....the tests confirmed that in both legs my Great Saphenopus vien had been compremised. The doctor ablated the GS vien in my right leg which got rid of the pain (he would not ablate both legs due an abundance of caution).
Hey man, I'm a physio student so I don't have extensive medical knowledge, but this pain seems like it aggravates during mobilisation and exercise. So it seems musculoskeletal, but it may also have to do with the neurovasculature of the lower thigh. Are their any signs or inflammation, any thing that indicate some tissue damage. Possibly it could be your muscular or neurovascular structures that have grown into that arrangement such that upon exertion there could be agitation of the nerves or muscle fibres.