http://en.wikipedia.org/wiki/Osgood-Schlatter_disease
Symptoms
A visible bump around 2cm in diameter will appear at the tibial tubercle and will cause pain during and after high impact activities, and sometimes after lesser activities such as climbing stairs. The disease is generally a benign condition which in most cases will eventually disappear on its own. Symptoms may last for 2-3 years, but will nearly always resolve at the end of the growth spurt, or at the latest when the tibial epiphysis fuses.
I have these symptoms only it is very painful to walk, and I have to get on all 4s to go up stairs, and I cant evne think about a high impact activity.