Some of the common conditions that cause calf pain are:

• Achilles tendonitis – the Achilles tendon is a strong band that connects the calf muscles to the heel bone. If your calf muscles are tight, it puts more strain on the Achilles tendon causing it to get inflammed. This condition, called Achilles tendontis, can cause calf pain. Tight calf muscles also put pressure on the plantar fascia and can cause plantar fasciitis. 
• Compartment syndrome – is a painful condition where pressure in compartments or groups of muscles builds up to very high levels that reduce the blood flow to the muscles. This prevents oxygen and nourishment from reaching the muscles. In case of exertional or chronic compartment syndrome in the calf, custom inserts or insoles can help relieve the calf muscles by redistributing pressure across the foot and by correction abnormal foot gait pattern and posture.
• Muscle strain and cramps – usually caused by dehydration or overuse, lack of warm up before exercise or sport, weak muscles