Congrats on the 12 days, and I'm happy to hear that your digestive system has settled it's strike.
I hope your concert won't be with a bunch of people who are drinking and getting high. That might be a little much only a couple of weeks in. I can tell you that it felt pretty odd going to my first concert, straight. I've been to several now, though, and lemme tell ya, it is GREAT to be able to really appreciate the music, and to remember it afterward. I have VERY little memory of the only time I ever saw the Grateful Dead. And it's a shame, because I will never get another chance to see them.