OK - I'm back. Sorry, my dinner was ready and I knew DS was going to wake in a bit so I had to type on the fly and quickly!
What was it that made the health vis decide that your daughter has lactose intolerance and not a milk allergy/intolerance? Did she say? Although many HVs have practical experience with this, through working with babies who have milk problems, I don't believe they are trained at diagnosing problems with milk in infants. And, sadly, neither are most GPs. I am very surprised that your doctor just accepted the HV's word for it that it is a lactose problem - is that what happened?
It does seem like she may have a milk protein allergy or intolerance. Infant formula is made from cow's milk, which contains lactose (milk sugar). Lactose intolerance in adults is common but in infants is very very rare. More common in infants is an intolerance or allergy to the milk protein. Soy formula is not made from cow's milk, but made from soya beans and so contains no cow's milk protein nor lactose, as lactose is milk sugar. Many babies intolerant or allergic to cow's milk are also allergic to soy -- the term MSPI is milk/soy protein intolerant. (Only a very minor diff between allergy and intolerance - allergy is an immune system reaction, intolerance is a digestive system reaction. Doesn't really matter if DD is allergic or intolerant, solution is the same - eliminate it).
Hydrosolate or hydrolyzed formula (Nutramigen, Alimentum) is made from cow's milk but the proteins are extensively broken down so that the body does not have to do the digestion and is suitable for almost all babies who are allergic or intolerant. It is also lactose free. Some babies can't tolerate even the tiny bit of milk protein that is still in these formulae and so they need to move onto an elemental formula (such as Neocate) where the proteins are FULLY 100% broken down. Usually babies are trialed on a hydrolyzed formula first.
At your GP appt tomorrow I would do two things - first, request a script for Nutramigen, explaining that you think DD is reacting to the milk protein. See what GP says - many GPs are hesitant to prescribe. Secondly, firmly request a referral to a paediatric gastroenterologist. Paed GI will be better at diagnosing lactose vs milk protein problem and more likely to prescribe specialist formula. If your LO has a prob with milk, most GPs would automatically (or should, IMHO) refer you to a specialist anyway.
We found Diprobase actually made my son's eczema worse - my HV prescribed it, HVs seem to love it! My GP gave us a script for Aveeno - just the plain old Aveeno lotion that you can buy in Boots - and coupled with the Nutramigen, DS's milk-induced eczema cleared up very nicely.
Do let us know how you get on! Be as firm as you need to with your doctor and take with you a notebook with symptoms, reactions, photos, descriptions of poop, EVERYTHING you can think of, to back up what you think. A lot of docs try to brush parents off as worriers over nothing, but it's much harder to do when armed with eveidence!
hope that is of some help?