I Have 2 Questions. I Just Finished A Dose Pack

I have 2 questions. I just finished a dose pack of prednisone. Would the medication cause me to have a few sores in my mouth. Just before the dose pack I had an injection of prednisone (which didn't help) for a torn rotator cuff. 2nd question: I am currently taking 400 mg of allopurinol...would missing doses cause inflammation or cause pain in my toes with walking, not resting.