If you'd busted the critter, the pieces would lose alignment, they'd wander away from each other, and you would've been unable to ride or walk. You would have known something was not right in a big way!
Something more like a crack (yup, still a fracture, but a little one) will stay lined up enough that you can still use the limb, but it won't be happy.
Docs seem to like to put casts or plates and pins on breaks, cracks they don't seem to worry as much and let you heal it on your own with weight or activity limitations.
Whatever it is, it doesn't feel like a normal barked shin to you, so I'd be running off to the doctor (hobbling?). But then, I'm a big ol' chicken! 
(cool bit of trivia: sometimes you can diagnose a crack that doesn't show up on xray if you run an ultrasound wand over the area. Cracks will hurt like heck when they are vibrated by the ultrasound, normal bone won't even notice it.)
"If Americans want to live the American Dream, they should go to Denmark." - Richard Wilkinson