I take levothyroxin for an underactive thyroid and if i don't take it every day i get those symptoms, but recently the symptoms you describe just kept hanging on and wouldn't ease, so i went to my GP and he said i had a virus in the muscles, and then added 'you've heard of M.E. haven't you?' and so I'm waiting to find out more about his casual diagnosis, if that is what it was! But certainly it couls mean in your case that you may need a review of your thyroixin dose. Mine hasn't changed in 15 years but the doc hasn't mentioned that option at all.