Pain across the bottom of the foot at any point between the heel and the ball of the foot is often referred to as "arch pain." Although this description is non-specific, most arch pain is due to strain or inflammation of the plantar fascia (a long ligament on the bottom of the foot). This condition is known as plantar fasciitis and is sometimes associated with a heel spur.
In most cases, arch pain develops from overuse, unsupportive shoes, weight gain, or acute injury. If arch pain persists beyond a few days, see a foot and ankle surgeon for treatment to prevent this condition from becoming worse.