Mucous in baby stools

My baby girl is almost 3 months old and has had mucous in her stools for the past few weeks. There is not always mucous but it is there more often than not. Her stools can be very dark green and extremely runny with much mucous. She is half breast fed, half formula fed on a lactose free formula. I don't tolerate dairy myself. I've been advised to try her on Soy formula but have read much negative research about it. Is mucous normal and what are your thoughts about Soy formula?

[boron]

Mucus in the stool is not normal. Causes may include parasites (worms or giardia which gives typical green stool), intestinal inflammation and cystic fibrosis (in this case mucus would be from the birth).

I recommend you take her to stool test for parassites.

Lactose intolerance, if this would be the case, would not result in mucus discharge.