First of all, welcome. Both to the forum and to the sport. Congratulations on surviving your bump in mileage. That is a great accomplishment.
Now to address your question. You might need a new saddle. However, since it is only your second week of riding, you need to get your butt used to it before deciding that the saddle is a problem. Even for avid recreational cyclists who don't train year round, the first few times on the bike after the winter can be painful. But after a short time, nothing hurts even after hours in the saddle. So, long story short, I recommend suffering through it for a couple more weeks and see if things just start feeling better.
If you continue to have problems, then consider a new saddle (fizik makes good ones), or even new shorts. Are you riding with shorts with chamois?