If you did not feed your bird anything different, then it is likely sick. You must get your bird to an avian vet right way. Keep the cage in a warm area until you can get the bird to the vet.
If you feed your bird food from grocery stores, then it could be that a chemical they feed the plant or spray on it for bugs poisoned your bird. Only feed your bird organic produce and still wash it well before feeding it to your bird. Remember to only give 20% treats, 80% healthy pellets to your bird.
Hopefully the next dropping will be fine, and you can cancel the vet visit. :-)