Rinse shrimp in cold water, drain, and set aside. In a small bowl, combine the seasoning mix ingredients. Combine 4 ounces of butter, garlic, Worcestershire sauce, and seasoning mix in a large skillet over high heat. When butter is melted, add the shrimp. Cook for about 2 minutes, shaking the pan gently back and forth. Add the remaining butter and fish stock. Continue cooking for another few minutes. Add the beer and cook for a minute or so longer. Remove from heat. Serve immediately in bowls with French bread for dipping or with rice.