In a large, deep skillet, heat 3 tablespoons of the olive oil until shimmering. Add the sliced zucchini and garlic and cook over high heat, stirring frequently, until the zucchini is just softened and beginning to brown, about 5 minutes. Add the shrimp stock, fettuccine, shrimp, tomato sauce, basil, oregano and the remaining 2 tablespoons of olive oil. Add a pinch of crushed pepper and simmer over moderate heat, tossing constantly, until the shrimp are pink and the sauce is nearly absorbed, about 4 minutes. Add the torn zucchini blossoms and toss just until they are wilted. Stir in the reserved pasta cooking water and season the fettuccine generously with salt and pepper. Transfer the fettuccine to a large serving bowl and serve immediately.