What Causes Pain In Legs?

pain in legs it feels as though there are bruises on the top of my calve bones (i forget the name of them at this moment). there is extreme pain when i walk, climb, sit on my knees, and any activity of the sort. i dance for college and the leaps we have been doing put extra pressure on my, what i am calling bruised bones . do you think i just banged them on something (i am a wild sleeper, it has happened in the past) or is it a sign of something more serious?