5 weeks pregnant with some kind of infection

Mama to a boy and one on the way

I found out June 4th that I was pregnant and also had a UTI. Well I am on Amoxicillin and for the past week or so I have had a greenish discharge. Today I now have a itch. My OB prescribed me Flagyl on Friday but I have not taken it because I have read it can cause a miscarriage. What can cause these symptoms and can this infection, whatever it is, cause a miscarriage as well? I am very scared.