Is there a link between stress and involuntary vomiting?

My boyfriend has been "stressed out", more than usual, for the past three weeks or so. First, he also caught a cold a couple weeks ago, which he NEVER gets colds because he is the healthiest people I have ever known, so this worried me a little. The cold went away in about a week but towards the end of it he was coughing a lot, a heavy chest cough as if there was fluid or mucus in his chest. Well, towards the very tail end of the coughing stage of his cold he would cough so hard that it bothered his gag reflex and he eventually coughed so hard that he threw up. I was moderately worried about this, but I myself have had this happen before, so I did not instantly insist he go to the doctors.  His cold has defused but he is still having problems with his gag reflex.
Basically now, he eats a meal and then he begins to feel like he is going to vomit. He cannot help but think about how he feels nauseous and he feels like he may vomit at any second, and then he actually does vomit. He told me that the nausea only seems to happen after he has eaten a decent amount of food, but his stomach does NOT become upset, get cramps or gas; and he does not self-induce his vomiting (i.e. sticking finger in throat). He simply begins to feel that nauseous feeling in the base of his throat and, again, he begins to focus on it because he doesn’t want to throw up; but he focuses on it to the point that he actually does throw up. The other day he was at work and his department had a luncheon and he ate quite a bit of food. A little later he began to feel nauseous and he became so paranoid that he was going to vomit at work, because he works in a bakery factory, that he stressed himself out thinking about it. It got to the point that he told his boss he had to go to the bank, left work in the middle of the afternoon, and drove down the street to a restaurant and threw up in a plastic bag that he had brought with him, in his car. This really worried me, that it had become so bad that he had done this and that this behavior has been happening for almost a week.
The only cause that I can think of that would explain this behavior is overwhelming STRESS.  He has had a lot of events happen within the last couple of weeks that have made him become stressed. He is sleeping ok, eating fine, and is feeling ok overall; that is why I am worried that it may be something else. His mother has a very bad history of anxiety caused ulcers and she herself does not handle stress very well. Also, my boyfriend actually took medication for anxiety for a short period of time about 7 years ago. Please let me know if I am on the right track or if something else may be the problem. Thank you.