I am avoiding dairy products because my DD was really suffering with ichy and weepy eczema on her face and other places. It came on when she was about 12 weeks old - we spent a month of trying different creams etc to no avail and then i tried avoiding dairy and eggs. The eczema is now lots better - gone, really and we are in the process of getting an official diagnosis from the docs.
Sometimes i find the diet restrictions difficult, but its really only junk food and puddings in restaurants that i can't have, which isn't really i bad thing. When i cook i substitute goats milk (full fat = lovely) or unsweetened soya milk, and we now buy vitalite marg. I use vegan recipes for biscuits and cakes (I've found some easy gooey chocolate cakes that i'm going to be baking for ever). I sometimes buy sheep cheese for sandwiches but have had to eat lots less cheese.
If I'm not around she has soya formula, which you can get from the supermarket.
She is 5 months now. I have been doing it for a month and I keep in the back of my mind that I could give up breast feeding but a chocolate binge isn't really that important to me.
Its not that bad. I would really recommend giving it a go for a few weeks to see if it helps.
It took a few weeks for the eczema to go, I think because i didn't give up eggs for the first week or so, and then i was drinking lacto-free milk (through not understanding what I was trying to avoid).
I ca't really offer any proper advice, just my experience. Everything i know I have learned from the internet (try the allergies board under health on MN). We are still waiting for our first dermatology appointment.