we changed Isabelle's formula so that it might help with the spitting up, but I'm not so sure it's…

we changed Isabelle's formula so that it might help with the spitting up, but I'm not so sure it's doing anything at all? it's been about a week now. sometimes she doesn't spit up at all, sometimes it cascades out like she's some kind of baby waterfall. The only difference is that it isn't chunky (vomit??), it's just runny, regular spit up. Also now her poop is dark green?? How long should I keep trying this formula? I tried to get in touch with her doctor but I got nothing.