An important lesson to learn from your experience with the Liver Flush is posed by the question; Why should you vomit?
I can't answer this question fully but people who suffer from a condition called gastro-paresis may have a tendency to vomit. After you consume the Liver Flush potion (Or any food) the digestive system goes through a cycle called the MMC (Migrating motor complex) cycle.
At the end of the cycle which varies considerable between people the digestive system enters a clean-up routine at this point is the stomach and/or upper intestines aren't clear it can induce vomiting. This is generally 3 to 4 hours after consumption.
You may have gastro-paresis and there are many causes and it is worth reading up about the subject.
I would advise people who suffer from gastro-paresis not to lay of ones back after consuming the Liver Flush potion. I recommend laying half way between the right and front to assist stomach emptying. Also to reduce the amount of potion by a half to start with and build up gradually in order to find ones tolerance level.