Can hear own breathing and ear feels blocked

I made an appointment to check on my ear but unfortunately the earliest appointment is in September but I have an important flight to take so I had to reschedule to December. I’ve been dealing with this hearing problem for quite a while and have trouble hearing people. It’s my left ear but I always sniff to clear it up but it comes right back. I can hear my own breathing and my own voice. I’ll have trouble hearing people in my left ear.

Is there any way I can fix it on my own or anything in the meantime before my ear appointment in December?

All help is appreciated ❤️