Tracey- Thyroid is a very easy condition to test for and to treat. It is a blood test, where they look for TSH levels, T3, T4, and sometimes hashimoto's antibodies which are abbreviated TPO.
If your TSH is elevated (above 3 or so) you can take a tiny hormone pill to provide the T4 hormone which will usually break down into the right amount of T3. It is no more difficult than takign a birth control pill.
Along with fatigue and hair loss, having thyroid problems will increase your general muscle pain and make repetitive strain injuries feel worse. I found my thyroid problems after I got TOS and treating it has made a big difference.
good luck