Hi Usually Allergy manifests immediately as sudden onset of breathing difficulty, swollen lips and tongue, itchy rashes on the body. And such a reaction is a life threatening one. Or late manifestation can be as rash, tummy aches, loose stools etc in cases of food allergy. Though nose bleeds are not seen in allergy, if it was itchy nose due to which he scratched the nose, then nose bleed would have happened. So possibility of peanut allergy can not be ruled out here. Hence its advisable to avoid peanuts. Hope my answer helps. Wish your son good health.