The dog doses are as follows:
Tylenol: 10-15 milligrams per kilogram of body weight by mouth given 2-3 times a day.
Aspirin: 10-20 milligrams per kilogram of body weight by mouth given twice daily
Most common side effects are related to the gastrointestinal tract. If your dog starts vomiting, gets diarrhea, stops eating, or becomes lethargic after you start these medications stop immediately and see your veterinarian.
Giving milk and Benadryl should not be needed nor have any positive effect.