6 week old with diarrhea

Hey everyone I would like some opinions on which formula to change my daughter too. I went to the pediatrician because my daughter is 6 weeks old and has had and still has consistent dark green watery poop. It's about 2x a day sometimes it leaks out the sides, she's a bit irritable at times especially at night. Doc said to put her on Gerber Good start Soy but I've read some reviews and some say don't, just asking if anyone has had the same problem I am having and what formula did you guys try.