Honestly, if it's long covid, the only real thing you can do is manage symptoms, and rest. I had covid in the winter, and things are just now starting to improve slowly. Rhinitis wasn't a huge issue for me, but shortness of breath and fatigue have been real problems.
There is no time frame for this, unfortunately. I know it's frustrating, and life altering, but continue working with your doctor(s) to manage your systems, and listen to your body.