midwest1

The back pain you describe sounds like sciatica. It's caused by a pinched sciatic nerve and is unlikely to be related to your hypoT. A good chiropractor can do wonders to re-align your vertebrae, which will alleviate that kind of pain.

As for the muscle pain... Muscle metabolism needs a steady, adequate supply of T4. Without it, muscles can remain weak despite concerted strength training exercise. Muscle achiness is a common thyroid symptom.