Well, in this 'The Land Before Time' fanfiction with Littlefoot being sick, perhaps his mother's spirit could appear to guide his friends. His friends could be divided on how to help him at first. Some might think they should keep him warm and find food near their home, while others would be eager to search far and wide for a cure. It could also be that Littlefoot's sickness is caused by something unusual in their land, like a strange new plant that has poisoned him. His friends would then have to figure out what it is and how to counteract it.
In the fanfiction, when Littlefoot is sick, his friends might go on a journey to find a special herb to cure him. They would face many challenges along the way, like crossing dangerous rivers or avoiding predators.