6 gallon Barrel Question

I have a 6 gallon barrel that I had been using to age beers in and I recently pitched a bunch of different Brett strains in it. There is a nice pellicle on top and everything seems to be going good however I am noticing a slight off flavor that I believe is vinegar/medicinal in taste. I am wondering if the staves in my smallish barrel are to thin and the beer is getting to much oxygen, promoting the growth of acetobacter. The beer has been in the barrel for about 6 months now, but it is not horrid that one wouldnt want to drink it.

Has anyone had any similar experience with smaller sized barrels and anyone have any idea if these flavors may fade out with continued age as the beer continues to sour?

It's not acetobacter. Well, it shouldn't be. Brett produces acetic acid in the presence of oxygen.

Vinegar taste = acetic acid. Smaller barrels will leave much more of your beer exposed to oxygen than a larger one. Therefore you can't age in them as long as a big barrel. If it was me I'd get that beer in a carboy or better bottle asap.

There are a few threads floating around on this topic that get into more detail.