Guys if you're having breathing problems this is how I personally corrected it:
1. Get a gym membership of like 6 months and make sure you have time to go there every day.
2. Go to the gym every single day for 5 hours or more. Constantly exercise to keep your heart-rate and breathing high. Your noses will come unclogged during this time and will probably clog up again as soon as you stop but eventually they will stay unclogged even when you stop until the condition of your nostrils being unclogged becomes the default most of the time.
3. Fill in the rest of the time with tumo meditation, aka focusing on your body and willing an increase of electrical activity throughout your whole body heating it up, and often pairing this energetic activity with the idea of healing too, imagining you are healthier every day and forgetting you ever were sick.
Also use water to unclog your nose regularly and wipe your mucus away on you a cloth you carry with you or on your sleeve or something, don't let social conventions prevent you from clearing your nostrils. Don't ever blow into tissue paper, blowing your nose into water or blowing your nose into your hand and then washing the mucus off your hand is preferable. Tissue paper just irritates your skin.
Anxiety makes it harder to breath, keeping your body warm and then doing stretches while warm and focusing on good archetypes will relax your body.