Vomiting while on birth control?

I typically don't post topics but this is something I don't have an answer to. I've been on birth control for about a year and a half, been taking it religiously at the same time every day, never missed a pill at all. I know that if you vomit or have severe diarrhea within the two hours you take your pill, it wouldn't be absorbed and you need to take a second pill and use a backup method.