Nissen Fundoplication question

My mom had Nissen Fundoplication (and hiatial hernia repaired)done today makes 1 week ago. She is having severe nausea and vomiting. She is actually able to vomit after being told it would be impossible. She is vomiting a dark colored almost like old blood stuff. She is still in the hospital. I want to know if anyone else experience this with their procedure? They're not sure what is going on...