Beat eggs until frothy. Mix with pork. Saute in oil, garlic, shrimp, and tomatoes. Add stock, salt and fish sauce. Bring to a boil. Add pork mixture to soup, breaking apart big lumps. Add celery and carrots. Bring to a slow boil for 20 minutes. Add noodles, simmer for 3 minutes. Add scallions and bean sprouts, remove from heat and serve.