Yes Marta,
Sorry about what happened. There are two levels about going off plan. One is that the off plan food really is not healthy, that is why you got such good results from the plan. The other issue is what I would like to share. I do not want to make light of what happened to you, but it has happened to me. What follows is a true story.
This happened to me but good one time. I think the term McDougall's revenge has been used from time to time. I had been very good for a prolonged length of time. I had lost weight and some of my coworkers were asking if I was ill. A friend at work told me I looked weak and that I should eat some meat or something. Well, I should have known better but the next day I had to drive a couple of hours with the wife and daughter to pick up my son at a rustic boyscout camp in the Mountains in a National Forrest. For whatever reason, my coworkers mischief worked its way on me and right before we left I ate a yogurt. Anyhow by the time I got to the camp I was in real pain. I could not even get out of the vehicle. I told the others I had to stay in the car and I reclined the drivers seat and lay "paralyzed" by a gas pain for about 45 minutes of agony. After that I was able to somehow get out of the car and made my way to a nearby Porta-Potty. The episode was concluded, except for me thanking the co-worker for her "advice" when I went to work on Monday. She was very sheepish about it. I learned a great lesson that weekend. First not to listen to critics. Second if I was going to listen, in no way fall off the wagon right before a two hour ride to mountains.
By the way, how to deal with co-workers and friends and family that might tell you, "A little bit can't hurt" is explained completely in the Doug Lisle DVD called the Pleasure Trap, available on this website. I recommend it to anyone, especially if you would like to avoid, "McDougall's Revenge".
http://drmcdougall.com/store_pleasuretrap.html