Good (No Tinnitus) Ear Blocked for No Reason?

Since yesterday I've noticed my left ear has been blocked after feeling a slight pressure change. It was very slight yesterday but today it is way more noticeable. I'm used to my right (tinnitus) ear being blocked every once in a while but never in this ear.

The weird thing is when I woke up today my right ear was blocked instead but while chewing gum which relieved it I got fleeting tinnitus in my left ear for 10 seconds and now it's back to being clogged again. As far as I can tell there's no hearing loss (my tinnitus isn't noise related anyway) and I haven't been around any particularly loud sounds so has this happened to anyone before?

It can be relieved after a hot shower but comes back around 15 minutes later.

Does this sound like it could be ETD or maybe I have some sinus congestion or earwax? I'm not asking for a diagnosis or anything just wondering if anyone has experienced this as it's making me miserable.

Thanks.