ICbaby,
Quite difficult to make sure your bb is feeling unwell or he is normal wow~! But if this made u feel very worry, how about u consider to bring him to see the Dr.?
I called this as "pay money" to buy my "heart" feel "secure" myself and I really did it last time as my bb is also my 1st baby (no experience at all).
Actually 2 days no "ng ng" should not be a problem, but if 4days then I suggest better have a check up with the Dr. coz if the "ng ng" never came out so long, once it came out would made the bb feel painful(very hard & dry already ma!)
i suggest u to go c doctor also if u r too worry but what i do to my jai jai (he pp once every 2-3days) is i massage his tummy every 2 days (when it's time to pp) when he was younger i lie him down and massage his tummy gentlely with both hands (fingers part) in circles and i make this "pull pull" noise too, when he's bigger (he's now 3months) i put him kind of sitting in between my thighs n do the same massage and noise, it works very well with him and he even understand it's pp time now 2!
hope it helps n good luck! x