Right swollen right foot, very painful to walk, downward step and release

Fracture?: Sounds like he needs an x-ray. A stress fracture can hurt like that. If the x-ray is normal then it could be tendinitis or a pinched nerve. Sounds like a trip to the podiatrist is the best answer.

Many possibilities : From tendonitits, fracture, gout, infection. You need to visit a foot doctor for an exam. They may decide on x-rays and or blood work to help with their diagnosis and treatment.

You may: Have a stress fracture. See a podiatrist asap.