Bad flavor question?

I made a honey Brown, about a month and half ago. After I kegged it I waited for about three days and tried it very happy with the taste, had few on and off for the next two weeks. In the third week when I was expecting it to be off the charts good I noticed a off flavor at the end, hard to describe almost like a plastic or ruber taste sometimes I think it tastes like bad grass. It has gotten worse now.

I have no Idea what happened I have noever made a beer that turned on me but this one did in a bad way. Any ideas what it may be. I did have some serious blow off on this one.

Very good reference for troubleshooting off flavors: … flavor.pdf

Check out the section on Chlorophenol.