Cаse A Funke Lаgоke, а 28 year-оld cоntestant on American Idol, was singing a duet with Ronda Felton, and then waiting to hear from the judges if she would make it to the next round of competition when she experienced severe weakness and dizziness. She proceeded to faint and fell face forward to the stage, lacerating her chin as she landed. She was taken to the hospital where she was treated with 3 sutures for the laceration and for dehydration. However, Ms. Lagoke reported that she had not been eating well and had been experiencing frequent episodes of weakness, dizziness, fatigue, and rapid pulse rate for the past several months. Her menstrual cycle had been unusually heavy during this time. Ms. Lagoke also reported that her tongue was burning and she often had difficulty swallowing. Use this case study to answer the following 6 questions. The clinical presentation is presented similar to the slide below. The most likely diagnosis for Ms. Lagoke is: