Thyroid problems. Yes, the hair problems in some cases are related to thyroids problems and some patients present headache , check with your dr, and family physician. We have to check and determine others possible causes, including but not limited to visual problems, hormone imbalance, anemia, vitamins deficiency, food intolerance ..., .
Possibly. The only way to know is to check it and see if it's the thyroid causing your problem. It's just a blood draw.
Yes. If your thyroid is under or overactive, yes. Sometimes thyroid antibodies can contribute to alopecia also. Please see your doctor to discuss this.