15 m/o poops every time we try put her to sleep

Basically what the title says. Trying to sleep train and she keeps pooping when we put her down. She cries for ages and sometimes I don’t smell the poop and then feel so guilty after.

She’s just stopped breastfeeding and adjusting to a huge increase in solids. Is she still adjusting or could she be doing this on purpose?

It’s making it so hard to get her to go to sleep on her own. She’s already difficult and now having to change her nappy during the settling process is making it so much harder and making her so mad.

I guess there’s probably not much I can do but thought it was worth trying to get some answers here.