Wow! This can be from so many things, such as;
Overused or stretched calf muscles
Misalignment of the foot, arch, ankle, knee, hip, pelvis, or spine.
Blood flow problems.
You need a Chiropractic examination to determine what the cause is. Treatment will depend on the cause. Call your Chiropractor and good luck!
1) foot pronation and a need for orthotics
2) chronic shin splints, easily corrected by stripping along the tibialis anterior muscle or posterior. Use oil or massage cream and massage the sides of the calf foot to head direction along the bone. This will probably offer the most immediate relief, but problem one may be the greater issue. Many Chiropractors can offer shoe orthotics