If you are pumping to relieve engorgement, make sure you are only pumping a small amount (only enough to be comfortable), maybe just an ounce or two. You don't want to pump completely dry at that point because it will signal your body to keep making milk and could cause the engorgement to get worse. If you are careful about how much you pump, you shouldn't have any trouble feeding again in an hour.
I'm not sure if you're asking about thrush in the mouth, but if so, you will see white spots on the tongue and insides of the baby's cheek. If you think your son might have it, be sure to have him checked out because you will both need to be treated so that you don't pass it back and forth. My daughter had it when she was little and it took forever to get rid of, but she was old enough for toys by then and it was tough to keep the toys clean so that she wasn't re-exposing herself to it.
I'm not sure exactly what you're asking about a diaper rash. If you think your son has one, you can use Boudreaux's Butt Paste (works great), Desitin, or Balmex. The cream I found that is the most effective though is from Arbonne. It's their herbal diaper rash cream. It is awesome. Everytime I have used it, the rash is gone by the next diaper change, but my daughter never got them that bad, so I guess it depends on how bad it is.
Congratulations on your new baby boy. I just had my second baby 2 months ago and his name is Aiden too (just spelled different)!