Drain pasta and set aside. In same pot, heat oil and two tbs. butter. Add garlic and red pepper and saute, do not brown. Toss in shrimp, salt and pepper to taste, stir until shrimp are pink but not cooked. Add spinach and oregano and stir until wilted. Return cooked pasta to pot, add remaining butter, Parmesan and parsley. Stir until well mixed and Shrimp is cooked. Add lemon juice, stir and serve.