You 100% are correct in taking him to the ER. You can't fool around with the eye, especially if there's puss.

I live in Canada and as you already know, we don't pay for health care - it's worked out in the taxes etc. So you can imagine our ER's are packed with cases that range from ridiculous to serious. We get people coming in with colds who think they can't wait for Monday morning. I once had pink eye and went to the ER -eye problems can't wait IMO