One month old with a cold

Hi all-Were having a tough week here. My LO just got a lip tie released and at the same time he came down with some congestion a coughing. After talking to a nurse we went to the ER and today the pediatrician. They think he just has a common cold but it totally freaks me out. He clearly feels bad and he’s so young to be sick. Any mamas have a LO get sick that early and have done wisdom on what to expect (length of cold) or tips to help them cope? Thanks!