The pain on the side of the foot can have several causes, commonly related to overuse, improper footwear, or injuries. Some typical causes include:

• Peroneal tendonitis: inflammation of the tendons running along the outer side of the ankle and foot, often caused by repetitive activity or ankle sprains. Symptoms include pain, swelling, and instability.
• Stress fractures: tiny cracks in the bones (often the 5th metatarsal) due to repetitive impact like running or jumping.
• Cuboid syndrome: partial dislocation or injury to the cuboid bone on the foot's outer side from overuse or tight shoes.
• Lateral ankle sprains: ligament injuries causing pain, swelling, and difficulty walking.
• Arthritis: osteoarthritis or rheumatoid arthritis causing joint pain and stiffness.
• Other causes can include nerve irritation, bunions, or inflammation of joints and tendons.

If the side of your foot hurts, it might be due to one of these conditions from overuse, improper footwear, trauma, or underlying joint issues. It's advisable to get an accurate diagnosis from a healthcare professional to determine the exact cause and appropriate treatment.