What Is The Cause And Treatment For Fatigue And Muscles Aches With Brain Fog?

Hi I suffer from fatigue everyday, aching muscles in shoulders I have been diagnosed with Hashimotos however all recent test tst have been fine so not on any medication for this and have anemia last blood test ferratin was 8 so on 2 iron supplement with vit c I have been feeling like this for a couple of years however feel like i am getting worse have bad brain fog and memory, fatigue, puffy under eyes and yawn all the time can you help?