V.F.
I was in the same boat. At 3 months old, my baby (now 7 months old) had small streaks of blood in her poop and the doctor diagnosed it as milk protein intolerance. He recommended that I eliminate all milk and soy products from my diet (I'm nursing as well). This seemed to help.
I started my baby on rice cereal mixed with expressed milk when she was 5 months old. She got a rash on her stomach and I waited 2 weeks to try again, and it was fine. Then, after she was eating two small bowls of rice cereal a day, I added oatmeal, which also did not go well. She was up a lot more frequently at night. So, her pediatrician told me to hold off on oatmeal until she turns 1 year old.
Still giving her two small bowls of rice cereal a day, I started to give her a couple of spoonfuls of sweet potatoes after she had eaten some of her rice cereal. I got this advice from a book and it actually worked. She ate it without a problem.
The slow method has worked for us. It sounds a little strange to me that your pediatrician would recommend giving your baby solids early because of an allergy. Usually they say to wait until at least 6 months when a baby has already shown signs of an allergy to food. What symptoms did your baby show of an allergy? Or was it an intolerance(a GI specialist clarified the difference to me)?