Congenital hypothyroidism

My baby boy is going to be a week old tomorrow and I just got the call today that he tested positive for congenital hypothyroidism. He has an appointment next week because at his first appointment (4 days old) he has not yet gained any weight. I made the mistake of googling it and now I’m super worried. Has anyone else gone through this? My mom had hypothyroidism and my husbands mom has Graves’ disease. I know it’s genetic, and I have been tested multiple times now which all came back fine... I just never knew it could be so severe. 😭