Maybe she ate something she wasn't supposed to? Momo does it all the time & he'll vomit, have gas, bloated tummy, & I give him some pepcid ac & he'll be fine.
I wonder why antibiotics were given.
It sounds like what ever she ate, came out (the green stuff). Does she have access to any plants in the house? Yeah, Momo used to eat our plants too, good thing they weren't poisonous.
Hope your baby girl feels better soon.