First, let me say I am sorry that you are going through this and your boy also. I know how hard it is to see them suffer. Please, please do not attempt to euthanize your baby using medication. The ramifications of an overdose are very very painful. They don't just go to sleep. There can be seizures, vomiting, abdominal pain and worse associated with this. By having your veterinarian humanely euthanize, it is much more peaceful. I am not sure what problems you had in the past making it unpleasant. I have had this done several time...unfortunately...and each time it was very calm for my beloved pet. Please discuss this with your vet if you feel the time is here. Good luck and may your baby cross the bridge in peace and wait patiently for you to join him.