I'm sure it was from falling off a bike and not running your new drug empire ;)
Stuff like that might as well get it check out and just make sure. Last thing you want is a lifetime of backpain if it was something that could have been dealt with. I'm not that wise not been to a doctor in a good 15 years.
The latter aids the former :D
I could do with my insurance card over here I guess, if/when I move and it's still not right i'll get it check. Doctor visits are few and far between also, plenty more in need of help from all that cola they drink!