About dark green stool. In pregnancy?

I am 15 weeks pregnant now.from one week I noticed that my stool was green colour.recently I used laycef antibiotics for 5 days during these days also stool is green colour.i stoped this antibiotic 2 days ago still I am getting green poop.what is the reason please help.moreover I am taking muesli which contains barley and different grains for breakfast and at dinner sometimes from one week.i don t know barley is good to eat during pregnancy.i am worrying about this.i don't have other complications like stomach pain or loose stools no pain etc.i am taking prenatal vitamin tablet after lunch.why I am getting dark green or green stools from one week.i am really worried about this.please help.and also suggest which foods I don't take in pregnancy?