My first road bike crash was when I was 13. My father and I were finishing our usual 15 mile route and were sprinting for the last corner. I ran over a rock I hadn't seen but seemed to be fine. 10 seconds later I started to lean hard into the turn only to have my bike slide out from under me. Turns out the rock had caused the tire to unseat from the rim and rolled when I tried to corner. The road rash on my hip got infected and green for a week after that and left a scar for years (testament to shaving).

Glad you're not badly hurt. Rails are a major source of concern to me. Not only are the grooves dangerous to get caught in, but wet rails also make your wheels slide out!

edit: Oh and good job crashing on the nondrive side.