What would cause this?

I am a 39 yr old female. I have hypothyroidism cause from taking a radioactive iodine pill to cure hyperthroidism and take supplements every day, though I have forgotten at times. I have tendonitis in both elbows from working at a computer for many years, though I am currently a stay-at-home mom. For years I have had stiffness in my back upon waking in the mornings as well as stiffness in my ankles and knees after sitting in one position for extended period, but both generally go away after getting up and moving around a bit. I am experiencing fatigue and tiredness as well as joint pain in my wrists, and fingers. The joint pain is more of a dull pain and stiffness that gets worse from being in one position too long, but never completely seems to go away. It seems to get worse when I am cold and taking a hot bath helps, though doesn't make it go away completely or for very long.