it's not a great photo, and it looks like you've got a lot of head space.
Is this whilst fermenting? or after it's supposed to be finished?
after the initial vigorous ferment, it might look like this.
once ferment is finished and it's clearing, or maturing, you really want to fill up to the top of the shoulder to keep as little air/liquid contact as possible.
there's not air lock there, so I'm guessing it's done first ferment, and is supposed to be clearing/maturing, in which case it might be Malo lactic fermentation.
as GA says, if it smells like vinegar, and tastes like vinegar, then it's probably vinegar. If it taste of farmyard, then it'll be the elusive MLF that you're after.
[resisiting the urge to make lewd comments about if I'd copulate with it or not]