Dont' take this as fact, as I'm not a doctor of any kind, but...I never saw vomiting as a product of suboxone. I saw mine vomit occasionally while he was using (heroin does a number on you digestive tract), going through withdrawal without the aid of suboxone, and after he had overdosed. Most likely, he won't tell you if he's using again so the best you can do is let him get sick and hope for the best. Don't be his nurse, take care of yourself first