If you were to have milk, in particular the low fat milks such as skim milk, this may result in increasing abdominal discomfort and gas formation. Products such as cheese and yoghurt are okay, as the lactose which you find hard to digest has already digested.
You can use Lactaid drops incubated in milk overnight, which would assist in the digestion of milk.
If you were to have milk, it should be in small amounts and it should be normal milk, not the reduced fat milks which have a higher concentration of lactose as mentioned.
Lactose can also be commonly used as a thickener and you should check to make sure that in different foods, food additives and sauces, lactose has not been used. It is also used in some of the artificial sweeteners and this should be checked on the container. Not all patients notice lactose intolerance, but it may be helpful on a trial basis.