Does anyone know if intense redness on a 5 year old's foreskin is normal?

For the past 2 days my son's foreskin has been really red. Just the tip where it hangs off the glands. However, it is not swollen. In fact, his seems smaller than it usually is, but that's probably due to the irritation causing it to recede. There isn't any redness on the rest of his body, other than his foreskin. Could it be an infection? Is the size reduction correlated with the redness? Do you think it will go away on its own? What could it be? He always wears cotton underwear and I did teach how to clean it. Should I give him some ointment? Our pediatrician won't be available until Tuesday so I hope I can get some help here first. Thanks.