Anon - Thanks for your question and for looking out for your health. According to the American Thyroid Association (ATA), most patients are able to resume their normal activities once they have recovered from the effects of thyroid surgery. Some patients, however, become hypothroid after surgery.
ATA states that when thyroid hormone levels are too low, the body’s cells can’t get enough thyroid hormone and the body’s processes start slowing down. As the body slows, you may notice that you feel colder, you tire more easily, your skin is getting drier, you’re becoming forgetful and depressed, and you’ve started getting constipated. Because the symptoms are so variable, the only way to know for sure whether you have hypothyroidism is with blood tests. Full article at: http://www.thyroid.org/patients/patient_brochures/hypothyroidism.html
You should definitely be checked out further and get answers as to why you aren't feeling normal. Please let us know what you learn as it could help others.
We wish you the best. Pat