Hi, welcome to the ehealth forum and I am glad to help you.
You seem concerned by the allergies, asthma and feeling of restriction in breathing when you play trumpet.You have also made a mention of nasal surgery last year.
You have not mentioned the nature of nasal surgery that you underwent but with the symptoms you have narrated there might be a chance that you have deflected nasal septum and/or nasal polyps. With the history of allergies the possibility of rhinosinusitis is also to be considered. The breathing difficulty might be due to physical narrowing of nasal passages due to above causes as during the time you play trumpet, you cannot breathe from the mouth. You might need a repeat surgery.
You must consult your ENT doctor for the definitive diagnosis and treatment as the same cannot be made online.
Hope this helps. Take care.
Note: This post is not to emphasise final diagnosis as the same cannot be made online and is aimed just to provide medical information and no treatment suggested above be taken without face to face consultation with health care professional.