I have 3 children and my middle child has a dairy intolerance, while my youngest has a dairy and soy intolerance. I nursed both successfully by eliminating those foods, though for the first month it was more difficult than it is now. After awhile, you really just don't crave the same foods. Advice: Rice milk is good on cereal but not a great drink! I buy Rice Dream Enriched Vanilla flavor. You can find it now in most grocery stores (they've come a long way since I first had to buy it!).
Personally, I HIGHLY recommend that you NOT add the product back into your diet until your son is on solids - just because it takes so much longer to get out of his system when he is strictly breastfed, and if there is still a problem with the food intolerance, you will both suffer much longer the earlier you try! Also, too much soy can contribute to raised levels of estrogen (which encourages cancer growth), so you really don't want to ingest too much of it anyway.
Okay, that is my 2 cents. :)
Sorry this is so lengthy! I have been thru this issue so much more successfully than many others I have talked with, and there is not much support for it! So many moms just put their kids on formula at the first sign of a dietary restriction! Good for you for hanging in there!
Blessings,
Angie