My "little man's" birthday is the same as yours - only he's 20 years old now!
Does your son retract at all yet? Does he play with his foreskin a lot? Little boys sometimes have grubby hands, so teaching him about handwashing, not touching his penis after wiping his bottom, keeping his nails trimmed, etc.
The rest is "body ecology" type stuff: identifying things that might lead to a chemical irritation or imbalance, eg. soap, chlorine, detergent, dehydration (busy boys sometimes don't drink enough), too much sugar in the diet. Also, since he's been on antibiotics, I'd make sure he has a course of some kind of probiotic (acidophilus product) to help balance out the flora and pH down there.
I'm sure others will have some good suggestions or insight for you!