Here is what she actually said:

"You know, as a medical doctor, there was a time when I looked very closely at those issues and not all those issues were completely resolved. There were concerns among physicians about what the vaccination schedule meant, the toxic substances like mercury, which used to be rampant in vaccines. There were real questions that needed to be addressed. I think some of them have been addressed. I don’t know if all of them have been addressed. At the same time, we have a real compelling need for vaccinations....."

https://shadowproof.com/2016/08/02/jill-stein-smeared-anti-vaccine-crank-sanders-supporters-consider-alternative-clinton/

You really shouldn't buy into smear campaigns from an establishment that is afraid of the left. Although it sounds like you are too.