You were the victim of poor advice and information, I’m sorry to say. Your baby wasn’t allergic to lactose. There is lactose in all mammal milk. Standard formulas are, of course, rich in lactose. If you used soy milk, and your baby did well on it, that suggests you had a case of Cows Milk Protein Allergy. Moms with that issue cut all dairy from their diets and go on to nurse just fine. Babies are never allergic to their mother’s milk, but they can be allergic to something in her diet. Dairy is the most common issue but there are other possibilities. A good IBCLC is essential if there are problems. Just urging a mom to keep nursing is a dangerous approach. The proper way is to observe the latch, listen to the swallow pattern, ascertain output via the number of wet and dirty diapers and, nowadays, to weight before and after feeds with a special scale. Breastfeeding is the biological norm and we owe mothers and babies better care so every nursing mother can have the help she needs. I’m sorry you did not get that.