If your pediatrician finds that your baby does indeed have a food allergy, this resource is one that really helped us out with our little one's food sensitivities:
Dairy and other Food Sensitivities in Breastfed Babies.
The source also explains:
"Some babies with allergies or food sensitivities exhibit fussy nursing behavior. Often when there is a sensitivity to something in mom's diet, baby will come to the breast hungry but when she tastes/smells something in the milk that will cause her GI distress, she pulls off, bats her head back and forth, etc. Sensitivities to foods in mom's diet are rare. If this is the problem, you will most likely notice other symptoms, such as excessive spitting up or vomiting, colic, diarrhea, rash, persistent congestion or runny nose, or excessive gas."
I know how frustrating and heartbreaking it is to watch your little one suffer ... especially when you don't know how to help them. And it makes everything so much worse when the "professionals," don't take your concerns seriously. I've always believed that a mother's instincts should be trusted. After months of watching my little girl suffer, and having the many specialists we saw all just shrug and refer us to the next "expert," we finally found that she had reflux (made worse by allergies) and I had a massive oversupply/OALD. I told all of those specialists that I *knew* something was wrong with my baby ... but even when she went on a nursing strike they all told me she was just being fussy (one lactation consultant even said, at 3 months old, that my baby was just a "brat").
Anyway ... stick to your guns! You are doing a beautiful job, mama!