no poop for 3 days already

Hello to all mom  i  just want to ask wat did u eat to make ur baby poop my baby stop of  pooping almost 3 days now. I give him and breasfeed and i was. Already in a doctor yesterday but all she say its normal. For the baby now  he is already 1 month and 2 weeks now. Is anyone can give a tip for me im a 1st time mom pls advice im just worried he dosent poop anymore for 3 days already  thank you advance xxx