No, it is not safe to use last year's ointment. Your genital rash could be a 'Fixed Drug Eruption' a specific allergic reaction to Norflox 400 or a new reaction. Using an old, potentially expired, or incorrect ointment can worsen the irritation and delay proper healing. You should stop taking Norflox 400 immediately and consult a doctor or dermatologist. They need to evaluate the rash, prescribe the correct treatment, and provide a safer alternative antibiotic to treat your dysentery. Please do not self-medicate.