A two month old with blood in the diaper can have one of several problems:
(1) blood in Bowel movement--possibly milk allergy
(2) Rectal fissure (unusual in breastfed baby due to no constipation)
(3) GI abnormality (polyp, etc.)
(4) Vaginal blood from foreign body as suggested by Dr. Newman
(5) Sexual abuse (yes, it can happen in a 2 month old)
(6) Vaginal abnormality
I, also, doubt very much that it is due to the breastfeeding in any way. It
should be evaluated by a good pediatrician, however.
Linda Shaw MD FAAP