You're probably suffering from shin splints. Any time your legs are use to one type of flooring then you change it will cause shin splints and are very painful. If you go from hard to soft or vice versa you will get them.

But concrete is very detrimental to growing feet and bones in a youth's body. Stress fractures can occur quite easily. I bet if you got an x-ray of your feet and legs your doctor would find evidence of healed stress fractures and depending on how long ago you changed floors current ones.