Welcome to the club. I too, am named Nick (not quite 32, but close enough) and yes, I've gone through almost the exact same thing, minus the weak legs. I ended up in the ER multiple times with an EKG connected to me and I've had a CT of my head and chest. All normal.
Fun fact: I'm going through a panic attack right now. That's why I'm on this forum. Hopefully my craziness will help settle your craziness.