Cheesy, vomit like, I've seen it before, perhaps not exactly what's going on at your gaffe but I agree that there are few things like a cheezy beer, especially when it's your own. Isovaleric acid is the marker compound. Smells like the Jacks in any Temple Bar pub on a Saturday nighgt.
Wild yeast infection, Brettanomyces was the culprit. It made for an interesting but totally unexpected Dublin dry stout.
Apparently, it rarely survives above 5% alcohol, making it difficult to culture from a higher gravity finished beer. Difficult, but not impossible.
In our case, I had no idea where it came from but we reacted with all guns blazing. Replaced all beer hose (upon inspection some interiors were cracked in the discard pile), broke down heat exchanger, replaced gasket sets (plates were not too bad, minimal deposits), cleaned and inspected all pump faces, cultured swabs of all hard piping before and after each junction, re-evaluated cleaning procedures and chemical application levels...and probably other things I can't recall. We were in the midst of yeast re-propagation so, we had a known pure culture to replace our pitching stock. Cultures of discarded pitching yeast, didn't find WY infection, even after numerous different media and techniques. Suspect it became resident in a too old piece of hose. Could be wrong. Still mystifies me.
Good luck with it.