Hmm that is strange. I've never encountered a fox, but I do know that like Karen said, they are shy creatures. Since I didn't see it I couldn't say, but I think both the mother leading away from den or illness related could be right. Animals are known to do anything to protect their young, but it is really odd for it to come up to you like that. I've heard of some animals like birds pretending they are wounded to get predators to come after them and away from the nest. The fox couldn't possibly be one somebody had tamed could it?