Thank you for your query at DoctorSpring.com
I understand your concern.
You're suffering from acute gastroenteritis and this needs antibiotic therapy. Norfloxacin does not cause any serious side effects. Only in some cases it can lead to some amount of muscle weakness but the incidence is very low.
So, please do not worry. I will rather advise you discuss with your doctor and start on Tab. Ciprofloxacin 500 mg twice daily for 3-5 days. This has very good effects on the bacteria related to gut infections like E.Coli ( the commonest cause ).
I am not sure why your doctor said it was dangerous, because Norfloxacin is a very commonly used antibiotic with good effects.
Additionally, I advise you also take probiotic supplements to help your digestion.
Feel free to discuss further,