Donkeys on the whole do not show their feelings of pain in very obvious ways, but behave as a human would who is called ‘stoical’, i.e. tolerating pain without complaint. They may make an initial violent movement of avoidance, but after that they become silent and as nearly as possible immobile in the face of pain and/or fear.
Therefore it is sometimes difficult to know when they are suffering acutely, and their behavior may look like ‘stubbornness’ rather than stoicism.
One indicator of pain or fear can be diarrhea, just as in humans. Since this may also dehydrate the donkey, it will be adding to its problems if it persists. A donkey who stops eating and drinking is at risk for death.
Please call the vet ASAP to save your donkeys life.