+1 on the possibility that it's a pediococcus infection
-1 on dumping it
Definitely keep it. Always give a bad beer some time. You can always dump it later, but you may be pleasantly surprised.
Years ago (14-15?), Sam Adams put out a Hazelnut Brown as part of their Longshot series. I decided to brew one. The recipe called for a full bottle of hazelnut extract, maybe a 40z bottle if I recall. I don't like the artificial nature of many extract brews so I cut it back to 1/2 a bottle. Well, it was still too much for my taste. I gave away a bunch of it at Xmas. A while later I moved. I wasn't able to set up my brewery for a while. Ran out of my homebrew. Found a few bottles of the hazelnut beer at the back of my fridge. Well, it was now maybe 6-8 months later and in the interim the flavors had melded into an earthy, rich, complex goodness. Really wished I'd saved more of it.
Anyway, that won't necessarily happen, but given time that beer may surprise you and be quite drinkable at the least.