Extremely dry skin, weight gain (even with careful eating and daily exercise), fatigue, losing my hair . could my thyroid be the cause?

Yes: Underactive thyroid (hypothyroidism) is a likely cause here. Other possibilities include viral illness and autoimmune conditions, as well as a few other less common medical conditions. Seeing the GP for an examination and to run blood tests such as for thyroid problem will help make the diagnosis here.

Possible : Underactive Thyroid can present as weight gain , tiredness, dry skin , constipation , irregular periods. Please see your Gp for blood test .