When the lungs are pressurized, they cannot take in oxygen.
As breathing deepens, the lungs that have not been used in the meantime come to life and grow. In order for the lungs to be large enough, the stiffened ribs and diaphragm must loosen. Or they are under heavy pressure. If the chest and diaphragm are not relaxed and the breath deepens, the lungs expand, putting pressure on all nerves, including the shoulders and back. The more stiff a person is, the more severe pain they feel. Since the pain is severe, I have doubts whether the training method is wrong, but I have to go through this process.
When the lungs are under pressure, nerves in the sinuses as well as in the nostrils become sensitive. If you have rhinitis, you should stop practicing and treat rhinitis first.