Did he have eye goobers & when you cleaned it, was it red underneath? Is it in the corner of his eye? Or is it someplace else....the redness? Bc when the eye goober has been there for some time, it will irritate the skin underneath & when removed, it will be red.
If the redness is not from eye goobers & it is under his eye, then it can be this:
Fourth Upper Premolar Tooth or Carnassial Tooth Problems
Here's the bigger pic:
http://www.2ndchance.info/carnassialLgfile.htm