My 13 mo old son has had a fever going up to 102.7 the last 2 days. It goes down with Tylenol . The wierd part is that when we put him down for his nap yesterday afternoon he woke up with hives on his legs (more on one than the other). They went away within an hour or two of him being awake He just woke up again at 5am and felt warm. I gave him a bottle and more tylenol. WHen i changed his diaper I noticed more hives on his legs again. So far the hives have only occured when he is sleeping, and seemed to get better when he was up and about. Does this sound like it is caused by a virus that will just run its course?