In a large skillet over medium-high heat, olive oil. Add shrimp, garlic, and red pepper flakes. Cook, for about 2 minutes until pink. Stir lemon juice; season with salt and pepper, to taste. Add diced tomatoes .
Bring to a simmer; remove from heat and stir in cream cheese, sour cream, mayonnaise, 1/2 cup nacho cheese.
Spread tortilla chips into a microwave-safe plate or bowl. Spoon the shrimp dip over the top of the tortilla chips. Sprinkle with remaining nacho cheese. Place in the microwave for about 1 to 1-1/2 minutes. (Microwaves times may vary.)