As you have learnt, IBS is a complicated subject and there are more than one type. Some types require fibre, some low fibre, and some are cause by food intolerances .
One view is that the bacteria colonies become disturb and even killed of by the over use of Antibiotics and suddenly there is insufficient bacteria to digest the food correctly. These bacteria aren't replaced because they are no longer seen as friendly. The bacteria colonies we have are fixed as an infant.
I don't think that Liver Flushing will cure your IBS problem. It may even inflame your IBS for a period because it temporarily upset the balance of bacteria and electrolytes. The Epsom Salts can be harsh for some people.