She should have told to the king what would happen immediately after the vision. He could have hidden an illness or have an allergia to the flower. The queen could also have poisonned the king during months or years.
@helper what would she even tell him? "yeah so I have those visions and I saw you getting poisoned, good luck" she also had a hypothesis that he wasn't poisoned so it would be bad if she told him he was poisoned and it turned out she wasn't