If and when we should see a doctor

Patient: My husband and I want to be certain-he is 24 and is experiencing flu like symptoms. He is constantly in the bathroom due to diarrhea and vomiting. At first his stool was full of undigested foods (such as the lettuce from dinner last night) But now the stool is mostly clear/greenish liquid, almost completely. His vomit was green (maybe due to the lettuce) and now it is bright yellow. He is experiencing severe abdominal pain right before he throws up and leading up to it. After he throws up he feels better.We have eaten the same foods every day for every meal, and I am not feeling ill, and I am pregnant. He does not have a fever yet that we can tell. My husband has a very fast metabolism, which makes me concerned that he isn’t eating anything. He never gets sick.Our question is, when should we go to a doctor about this. We hope it is just the flu, and it is gone soon, but we want hear your opinion.

Symptoms: Abdominal pain, vomiting, diarhea