**Core Concept**
The underlying condition is likely related to the musculoskeletal system, specifically involving the medial aspect of the lower limbs. The symptoms suggest a condition that affects the muscle or its surrounding structures, exacerbated by physical activity.

**Why the Correct Answer is Right**
The presentation of pain at the posteromedial aspect of both legs, with acute point tenderness, is suggestive of **Medial Tibial Stress Syndrome** (MTSS), also known as **Shin Splints**. This condition is often associated with overuse or repetitive strain on the muscles and bone of the lower leg. The tibialis posterior muscle, which runs along the medial border of the tibia, is often implicated. Physical activity, such as running or marching, can exacerbate the condition by increasing stress on the affected areas.

**Why Each Wrong Option is Incorrect**
**Option A:** **Achilles Tendinitis** typically presents with pain and stiffness in the posterior aspect of the ankle, rather than the medial aspect of the lower leg.
**Option B:** **Osgood-Schlatter Disease** is a condition that affects the growth plate of the tibia in adolescents, leading to knee pain and swelling, which does not match the given symptoms.
**Option C:** **Compartment Syndrome** is a condition that involves increased pressure within a muscle compartment, leading to pain, weakness, and paresthesia, but it typically presents with more severe symptoms and is often associated with trauma or prolonged immobilization.

**Clinical Pearl / High-Yield Fact**
The term **Shin Splints** is a colloquialism that encompasses a range of conditions affecting the lower leg, but Medial Tibial Stress Syndrome is the most common and well-documented condition associated with this term.

**Correct Answer: C. Compartment Syndrome.**