I also have this problem for some weeks now. I used to practise valsalva maneuver, and then stopped because I heard that you shouldn't do it. The ENT's told me this was fine, but they know nothing. Well, now I have this instead. I also notice that my tinnitus seems to spike.
Do you know why this happened for you. Do you still have this problem?
I've had this problem for years now, but never found anything on the internet about my problem. Telling the doctor about it got only a "huh, that's weird...", which isn't really a surprising response considering how absurdly specific the problem is. I've never had a problem with the burping until I got tinnitus in my left ear from another incident, after I got tinnitus in my left ear I discovered the burping actually spiked my tinnitus, and dulled my hearing--of course this could be caused by anxiety and/or stress from worrying too much.
As for the question if I know anything about this condition... I don't really understand why this happens, why it's only my left ear, and why it seems to be only me with this problem, etc...
I know doctors warn people against holding in sneezes because the rapid expulsion of air from your lungs can easily enter your ear canal through your throat and rupture your eardrums, which is sort of what's happening to me, except it's an involuntary action--I don't consciously hold in my burps.
The only thing I know is that I have GERD, which causes overproduction of stomach acid, which in turns leads to me unconsciously swallowing a lot of air into my stomach, which comes back out as gas. I find myself burping every few minutes, especially during movement, and I try very hard to consciously not hold it in when burping. The only thing I can do is try to control how often I burp so I've been taking Ranitidine in the hope of controlling my stomach acid, but it hasn't worked that well, other lifestyle changes including smaller meal proportions haven't resulted in any improvement since I'm burping excessively even on an empty stomach. I'll be visiting a doctor soon to get a prescription for PPI medication, which is very effective for GERD sufferers and should hopefully mitigate the stomach gas issue, and as a cpnsequence, my tinnitus spikes as well.
tl;dr if you have the same problem try controlling your belching with medication