I have a 21 year old son who was born at 31 weeks (no complications - steroids administered prior to birth - 30 mins oxygen after birth) Home from hospital after 5 weeks. Suffered from acne at 17 took a course of roaccutane. Wisdom teeth removed at 19 years old. 194cm and 100kg. Doesn't smoke or take drugs. Goes clubbing/Drinks one weekend out of 4. Goes to the gym 3 to 4 times a week for weight training (not cardio) Takes pre work out stuff and has a protein shake after the gym. The problem we have is that he has suffered from a chronic dry cough for approximately 3 years. It is a deep cough that often gives him a headache. He has seen a GP and had tests for asthma, infections, blood tests etc - nothing unusual was picked up. I'm not sure what to do next. Do you have an advice??