K.W.
I know you were scared and shaken by that experience. Food allergies are so sudden to healthy children (and adults) that we forget how vulnerable we are to what we eat. I agree with the others that it could be something you ate or the potatoes. At this age your baby really gets adequate nutrition from your breast milk and a little cereal. Perhaps you can hold off on the potatoes until your little guy is somewhat older and if you are happy with vege's and cereal, then go with a blander solution like carrots, peas or green beans for now. Also look at the preparation, was there peanut oil in something you or your child ate? That tends to have a very sudden and severe reaction. The other things you can look at is any family allergies that perhaps you didn't now this baby may have inherited. You really have to put on your Dr Watson and Sherlock Holmes hat sometimes so it is good to work thru this with your pediatrician.
Good Luck to you and your little ones. Have a very merry christmas.
K. @ The Nesting Place