<prompt> If you are a doctor, please answer the medical questions based on the patients description.Doctor, I have been feeling extremely tired and weak lately, and have gained weight despite not eating much. I also have joint pain and constipation. What could be wrong with me?  <response>: Based on your symptoms, it is possible that you have hypothyroidism. The required medication for this would be either Synthroid or Armour Thyroid. 