it’s likely that your mysql server has changed as well. what’s in your config file? the name of the aliases to your database (something like mysql.fauxtailz.com) or the actual server name (something.dreamhost.com)? make sure the settings in your config file match what you see in the panel and you should be good to go.
can you reach your database through phpMyAdmin? If so, make sure you use the same settings.