Why do I have continuous ear hissing and fullness?

It appears you are going through allergic rhinitis, which is responsible for your runny nose, swollen eyes, ear pressure, sneezing, and breathing difficulties. These symptoms have been persisting for a long time despite trying different medications. The allergy shots that you are receiving may have expired, thus not giving you enough relief. Seek consultation from an allergist to review your treatment plan and consider updating your allergy shots to manage your symptoms effectively. 

To get your nasal septum surgery, you need blood tests and maybe a nasal swab. The surgery is expected to last from 1-2 hours. The recovery time may be different, but you might have to keep still for a few days. Your old CT scan is nice, but doing the new one preoperatively is a good idea. Your case is not so serious, however, the surgery will be a positive thing for you in terms of breathing and reduced infections.

It sounds like you're experiencing typical symptoms of a common cold, which can affect sinuses and lead to feelings of pressure or fluid in the ears. This sensation, along with diminished hearing, may result from fluid buildup. For relief, consider using a warm compress on your ear, staying hydrated, and trying steam inhalation to help clear sinus passages. Over-the-counter decongestants may also be beneficial. If symptoms persist or worsen, please consult a healthcare professional for further evaluation and guidance.