What do you mean by 'infected'? Was it an accident or did you pitch the brett on purpose? Brett primary or added brett to a sacc primaried beer? It's been fermenting under pressure in the keg or you've got it set up as a fermenter?
I did a Brett C dark ale - hesitant to call it a porter, but porterish grist. Had the burning electric smell bad early in the fermentaion, but that eventually cleared as the yeast re-metabolized the compound that makes that awful smell. My beer went through that phase in under a month, so at 4 months in yours could be stuck with it. What sort of dark malts did you use? I think it might have something to do with that. Chad Yakobson recommends not using much if any traditional dark malts or roasted barley and instead using de-bittered products like huskless carafa for color and less astringent 'dark' flavors in all brett fermentations.