I’m An 83 Year Old Woman With Osteoporosis. My Doctor

I’m an 83 year old woman with osteoporosis. My doctor urged me to take Fosamax for two years. I finally took it for a one month period. Even before I took the last pill, I started having side effects. That was in April of this year. I’ve experienced weekly illness (every side effect listed) up until now. It is getting less. Why has it lasted so long?