thank you for the help ! i'll stick to it
Advice from your doctor seems to be appropriate, and if you stick with that diet, and the cause was lactose or fructose malabsorption, it should really help in three days.
The point is that the diet has to be strict.
Lactose is not only in dairy, but as an additive...elswhere..in chocolates, dry mixes, sauces...
Fructose is in all fruits (apples, pears, dates, figs, sweet cherries, pears are the worst!) From vegetables avoid asparagus, leeks, artichoke, onions and tomatoes, including ketcup. Frozen and commercially breaded meats contain fructose. Packaged meats can be sweetened.
In short: no dairy, no fruits, commercial sauces/salad dressings, and no pre-prepared/tinned, packaged food at all - this is the easiest to remember.
After some time you'll see, if you have both lactose and fructose malabsorption or not.