Heat a Dutch oven or large saucepan coated with cooking spray over medium-high. Add onion, bell pepper, and garlic, and sauté 5 minutes. Stir in cream cheese; reduce heat, and cook until cheese is melted. Add milk, corn, soup, and tomatoes; cook 10 minutes, stirring occasionally. Bring milk mixture to a boil. Add shrimp; cook 5 minutes or until shrimp are done. Remove from heat. Sprinkle each serving with green onions.