No fears, love. We all have gone through that. To let you know, a slight fever is generally nothing to worry about.. Also, could just be cranky because he is sleepy, hungry, thirsty, or, really, just wants to be cranky.
What I always went by, given to me by hv, is to not worry if the \'fever\' is under 37.7 degrees in the morning or 38.2 degrees in the evening. That is just your little one getting used to life! :)