Yep... been there, done that.  I had appendix flare-ups for years, and the docs always said it was the stomach flu.  They finally removed it almost six years after my initial flare-up when it burst.  Good times.
I've had maybe only one experience that was more painful than the whole appendicitis bout, and that was when I broke both my back and sternum at the same time by jumping off of an 85-90 foot cliff.  I had to climb my way out, walk back to the car, and then sit through a 45-minute windy drive back to the apartment, which is a LOT worse than it sounds.  I couldn't sleep because both my front and back sides were broken, I was hyperventillating for weeks, and yeah.  Day before my birthday, same day my G-ma ended up passing away, and the day after my health insurance ended.  I was working two weeks later, which is insane, but I was bored.  I'm still having complications two years and three mouth/jaw surgeries later.