3 week old poop question....:/?

You could talk to your dr about a soy based formula. my daughter had a terrible time pooing until she was around 2 months old. his little body just isnt used to breaking down formula yet and it will come in time. there are other things you can try besides using a thermometer. a warm wash cloth of his tummy, bicycle movements with his legs, holding his legs to his tummy gently being sure not to push them, rubbing his tummy firmly but gently. honestly if your dr isnt willing to check him out and figure out what is going on then it may be time to find a new one.