What Causes Severe Pain In The Calf?

my 10 year old daughter started gymnastics in January and is now having severe calf muscle area pain when running, jumping, rebounding type exercise. Not at night not just walking not just sitting.. She also has been experiencing severe headaches since she was in 2 nd grade and just since January we have been working on finding out what could be wrong with her head. Could all of this be 1 big sign of something big? We have seen an orthopedic for the legs and took xrays... no stress fractures. they say time off of gymnastics should heal the leg problem. We did blood work for the headaches, it came back normal. now off to have a catscan done. now my grandmother died of Renal Cell cancer which moved into her leg bones, could this be an issue?