You ask some excellent questions! In fact, some of your symptoms do sound like they could be from an underactive thyroid. Symptoms of thyroid dysfunction include hair and skin changes; irregular menstrual cycles in women; feelings of being either too hot or too cold; weight gain or loss without a significant change in diet or activity; and palpitations. In short, because thyroid hormone affects all parts of the body, many different organs can be affected if the level is not appropriate.
However, there are other conditions that can cause fatigue and hair changes, including some infections and nutritional problems. In addition, feeling fatigued, a sudden increase in urination, and vision changes in someone of your age can also be the presenting symptoms of diabetes.
The bottom line is that given your new symptoms and the broad range of possibilities that could explain them, the best thing for you to do is to see your primary care physician
right away. He or she can go over your entire health history, including these most recent symptoms and your family history. A physical exam will be very helpful in pointing towards a possible explanation. In addition, your doctor
will likely want to run a few basic lab tests for further evaluation. Together, all of this information should help to determine what is causing these new symptoms you have been experiencing.