I doubt that cough drop water would help him in any noticeable way. His tonsils are swollen and very sore. I've had tonsillitis many times and cough drops did not help. In fact they cause more pain because I had to swallow more.
If you're not giving him acetaminophen or motrin, do give him one of those. Unfortunately there is not much you can do for tonsillitis. I think it's a virus, tho you could call the advice nurse to be sure.
Putting chest rub on him is also not going to help with the tonsillitis. It's his tonsils that hurt. Chest rub only helps with breathing if he also has nasal congestion.