pumpkin beers have the pumpkin added during the mash or boil - never later on. Adding something later on brings on chances of getting what you have now : an infected batch of beer. My suggestion is to rack out from under the scum and off of the pumpkin slurry and let it sit in a dark place for a while.
why did you let the beer sit in the bottlng bucket for that long? if I bottle something it goes into the bottling bucket, gets its priming sugar addition, and then goes directly into bottles. Were you using the bottling bucket as a secondary?
just so you know, pumpkin adds almost nothing to a beer - the flavors are usually from spices. You might get some mouthfeel but not too much.