Sore, stiff muscles happen to some hypothyroidians after exercise. T3 helps, magnessium glycinate or taurate is one of the best magnesium types for muscle pain - other types dont work as well. Magnessium citrate is the second best but effects bowls more.
Its important to have the correct hormone level, need to be optimal. Not just in range. Most feel best on natural thyroid med with Free T3 in the upper third of the range despite the low TSH this can create.
If you exercised for years and had injuries while hypothyroid but were not yet diagnosed, this can damage muscles making adhesions causing more pain even after taking thyroid med.
Fatigue is another hypo symptom or not enough thyroid med. Still some just arte not like they used to be and need B vitamins , plus vitamin D-25 test should be 50 or higher.
I never really thought of these symptoms being similar flu symptoms. Sick VS sore and tired are two different things to me. Hypo doesnt make your nose run.
Forgot to add. Creative stretching is very important for hypothyroid people experiencing body pain. Using a foam roller and a tennis balls or soft ball to roll over muscles (roll on floor) to break up muscle adhesion and small knots helps in upper legs, glutes, hips and lower back. U-tube for ideas.
In extreme cases Chiropractors or Physical therapists that practice trigger point release (static) and Active Release (moving) can break up muscle adhesion that cause the pain. It works to some extent for most people.
Thanks for the comments, nice to know someone is reading these things. When I say flu-like symptoms it is about as close as I can get to explaining the debiliatating achy sensations--really kind of different than just being sore. I am have been very physically active and kinesthetically aware for a long time and have a great deal of familiarity with soreness. The achy problem really is more about aching--kind of like my muscles and joints desperately aching for some kind of relief. That combined with the fatigue is very similar to me with aspects of the flu, and although there generally is no runny nose or fever there does generally seem to be a mucus related component as well as occasional mouth sores.
I do quite a bit of stretching and that helps so nice to be reminded and encouraged to do that. Anyway, thanks for taking the time to respond.
Just wanted to respond to the comment "Thanks for the comments, nice to know someone is reading these things." Lots of us are reading and waiting for the answers too. We are just to timid to even write, much less confront the Dr. Thanks for posting your situation.