i was going to say the 4 month thing as well. DS has never been a great sleep & around 4 months was a nightmare. it could be worth checking things like reflux - can you hold her till she falls asleep & then put her down? or keep her a bit upright after a feed & then put her down? if she has a bit of reflux that might help

for us it was just a matter of waiting things out but hopefully your naturopath can give you some answers