Blood in stool

My baby will be 2 months on June 8th. She had a small amount of blood in her stool on 5/11 and the doctor said to watch her and see if it happens again. She said if it does then the baby is most likely allergic to diary and I would have to cut it from my diet. She is only breastfed. She had another small amount of blood in her stool on 5/23. I’m not sure if it’s the diary allergy or something else since the 2 occasions were far apart. Anyone else have an insight??