My Dad is 70 years of age. He has atrial fib, high blood pressure, and takes a blood thinner. He took 50 mgs of an amitriptyline pill the other night and slept that night and the entire next day. On that following Tuesday, he was unable to breathe, and was taken to the ICU. They cannot see any problem or reason for his breathing problem, and he's currently on a ventilator. Would this pill have caused this problem?