Preheat oven to 350 degrees. Boil chicken until no longer pink inside or out, and shred. Mix chicken, soups, and tomatoes in a large bowl. Spread mixture in a deep rectangular baking dish. Sprinkle 1/2 shredded cheddar cheese over mixture. Top with Doritos (enough to cover). Sprinkle remaining cheddar over the top. Bake at 350 for 20 minutes or until cheese has melted and mixture is boiling.