Baby constipated

Ashley
Can anyone give me advice on my newborns constipation?!? The past two days we transitioned to nothing but straight breastmilk. Before that I was told by my drs to supplement for a little while because she was jaundice and they wanted it for weight gain too. She was on similac sensitive the first three weeks with a mix of breastfeeding in-between. I can count on both hands how often she has pooped since birth. Her belly today looks very distended, she's passing smelly gas all the time and today started spitting up more than usual. She feeds 2-4 ounces every 2 hours. Her weight is up from birth and is constantly wetting diapers. My dr didn't seem concerned about it at all..he said some babies go every 15 mins and some go once a week. She isn't crying that she's in distress, but the spitting up,smelly gas and distended belly has me worried. She will be one month on the 14th..any opinions on what I'm experiencing or things I can do to relieve her? I'm calling the dr tomorrow because this just doesn't seem right!! But any thoughts would be appreciated!!