Hi
First of all there are two different types of exercises stretching and strengthening... Doing stretching Wil not improve your muscle strength. U need to strengthen your quadriceps, hamstring and calf muscle. So u Wil have to do strengthening exercises on a daily basis.
Next Steps
U can see an orthopaedician.. May b u Wil also require few supplements for ur bone strength
Health Tips
Avoid sitting cross leg or sitting low.