Pancreatitis can certainly make a dog feel very sick, and off food. In fact food is off the agenda with pancreatitis anyway. The pancreas has to be forced to 'rest' in order to heal. I.V. treatment is usually the best plan in order that the dog will be kept hydrated.
High blood calcium can indicate cancer. But of course, you do not know unless the tests are run. There could be another cause. Addison's Disease can cause hypercalcemia.
Also, are you absolutely certain he couldn't have got into rat or mouse poison? Or recently eaten a rat or mouse which may have been poisoned? Some rat and mouse poisons contain large amounts of Vitamin D and are toxic. Exposure to that can also cause elevated blood calcium levels.