Since I was a child I have had this problem but recently is getting worse.
To note: I have never had an ear infection in this ear and have already checked it is not due to earwax at the doctors.

My left ear feels like it blocks, this can be for no seeable reason, but more consistently if I'm doing exercise and breathe through my nose. It makes it so I can hear myself speaking and breathing really loudly in my head (like when your ears need to go pop) but everything around me becomes muted.

Over the past two years it has gotten worse because it feels like there is something under the back of my tongue (also on the left) which is makes it harder to speak. This is apparently getting more noticeable as friends are pointing it out.

Does anyone have any idea what might cause this?