Quadriceps Strain: This is the most likely diagnosis given the mechanism of injury (sudden contraction of the quadriceps while kicking a ball), the location of the pain (right quadriceps region), and the nature of the pain (initially severe, sudden onset, and exacerbated by specific movements). The patient's ability to walk immediately after the injury but experiencing pain upon attempting to kick again further supports this diagnosis.

Quadriceps Contusion: A direct blow to the quadriceps could cause a contusion, leading to pain, swelling, and bruising. Although the patient does not mention a direct hit, it's possible that the mechanism of injury could have involved an indirect trauma to the muscle.
Patellofemoral Pain Syndrome: This condition, characterized by pain around or behind the patella, could be considered if the pain is more localized to the front of the knee and is exacerbated by activities that increase pressure between the patella and the femur, such as climbing stairs, squatting, or sitting for long periods.

Femoral Fracture: Although less likely given the patient's ability to walk after the injury, a femoral fracture (especially a stress fracture) could present with sudden onset of pain after a specific incident and should not be missed due to its significant implications for treatment and potential complications.
Deep Vein Thrombosis (DVT): While the presentation does not strongly suggest DVT, any condition that causes significant leg pain and swelling should prompt consideration of this diagnosis, especially in patients with risk factors for DVT, due to its potential for severe consequences if not treated promptly.

Osteosarcoma or Other Bone Tumors: These are rare but could present with pain in the affected bone, which might be exacerbated by activity. Given the acute onset related to a specific incident, this is less likely but should be considered in the differential diagnosis, especially if the pain does not resolve as expected with rest and rehabilitation.
Compartment Syndrome: This is a rare but serious condition that could occur after a muscle injury, characterized by increased pressure within a muscle compartment, leading to severe pain, swelling, and potentially permanent damage if not promptly treated. The patient's report of muscle spasms could be a clue, although the absence of other classic signs (such as pallor, paresthesia, poikilothermia, and pulselessness) makes this less likely.