Advice on blood in poop

So my baby has had blood in her stool since she was 6 weeks old. She is now 17 weeks. It’s off on. I told my pediatrician and he said that it is a fissure in her butt hole. She never seems to be in pain or crying. She’s a happy baby. I don’t know how to heal this Fissure. I have done Aquaphor, Desitin, now I am soaking her booty in baths. It’s alarming because it’ll be gone for a few days and then return and it will be bright red. Do you have any advice as to what I should do? Her poops are not hard. She is exclusively breast-fed. Her poops are typical ebf poops.