My infant son has a red ring around his circumsized penis. It seems to bother him a little. What could be the cause or treatment for this?

Irritation. Generally some redness around the remaining skin on a circumcised penis is a local irritation, with a local skin infection also a possibility (so many bacteria in the perineum!). The best thing to do is use water to wash the area (no soap or wipes), and put some a and d or even a little antibacterial ointment on the area).