Thank you . Ouch that looks itchy and painful. It is possible that he had another bur that started the itching and scratching. In some cases this can lead to a secondary bacterial infection. Because he is white the sun could also be causing problems with the skin and many white cats will actually develop skin cancer on the face and ears.
Since he tends to lick more when you actually put something on there what I would suggest is cleaning this with either anti bacterial soap or Betadine diluted to the color of tea 1-2 times per day.You can try over the counter Chlor-Trimetrone to help with the itching. This is dosed at 2-4 mgs once per day.
If you think you can give him to leave anything on for a few minutes I would try the neosporin with pain relief to numb the area.
Since he goes out it could be something else that he is reacting to such as a plant or even grass.
The glass food and water bowls are great and allergen free.
If this continues to happen I would suggest the following
* Try a complete allergen food such as Science Diet z/d this food is broken down to the point that the body can not identify what it is getting so there is no risk of reaction.
* Ask your vet about trying Atopica. Click here
* Get allergy testing to be sure this is truly an allergy you are dealing with and not a problem with the immune system such as pemphigus. Allergy testing will also tell you every food and environmental allergy he has Click here
I hope this helps give you some options. Please reply back if you have additional questions and I will be happy to continue.