Hello, Welcome to HCM, Difficulty breathing may be related to varied causes such as: 1.Problems with the lungs such as asthma. Since you are a known asthmatic and having trouble breathing, an acute asthmatic attack should be considered first of all. You need to speak to some one and get assessed quickly 2.Nasal obstruction due to infection, allergic rhinitis, mass in the nose, abnormal structure of the nose 3.Any obstruction or abnormality along the upper airway-pharynx, larynx, trachea 4.Heart disease 5.Anxiety- this is only considered if the other conditions are ruled out. Thank you.