Hi, my 15 month old has had peanut butter for the last five months. This morning, he ate a peanut butter banana breakfast bar that I made him. He now has what looks like hives on his back and belly, but is acting fine - no trouble breathing, no itchiness. Could he have all of a sudden had a reaction to the peanut butter? It's all I can think of that would make him break out like this. He is teething, but I can't imagine that would make him break out. Any thoughts?