One thing to remember with our little ones: They do not really get that dirty - except for the diaper area. (And this can be cleaned rather well in a change).
They do not need to be bathed daily - maybe once a week at the most as they need those protective skin oils their body makes.
Diet & Environment also play a factor.
Laundry detergent may be a culprit in addition to what is going on.
Something else to keep in mind: If you would not eat it~ Do not put it on your skin - especially your children's very sensitive skin as it takes only minutes (20 minutes at that) to absorb into their bodies.
A great moisturizer: cold pressed olive oil~ use it rather sparingly as it goes a long way, but it works wonders at giving your son a massage and a great bonding time for the both of you!