Debris in Sockets or. The socket in your jawbone can collect debris until it heals and fills in with bone covered by gum tissue. In the meantime, your oral surgeon should give you an irrigating syringe to squirt in the hole(s) to keep them clean. Could also be blood or possibly drainage/infection. Does it hurt? Getting better or worse? Any q's, see your dentist.
Could be infected. Followup with the dentist that removed it.
Bad Mouth Taste . There was a blood clot that formed and filled the socket where your tooth once was . Ideally, the clot will solidify and stay in place. New tissue grows through the clot during healing. The byproducts of the breakdown of blood down during healing will give you the bad taste in the mouth. If there is significant pain associated, it may be an infection. Call the dentist who extracted the teeth.