In a large nonstick skillet, heat olive oil over medium heat. Add peppers, onions, mushrooms and garlic and cook until tender - about 8 minutes. (Lower heat to low medium if needed to avoid browning). Add worcestershire sauce to veggies and stir well.
Sprinkle sliced chicken over veggies in skillet.
In a small microwave-safe bowl, mix cheese and tomatoes and heat until melted. Pour melted cheese over chicken and veggies in skillet and serve.