Welll, as to your son's fevers, I can't comment. However, I will typically run hot/cold. I picked up the thermometer, and sure enuff, I would jump up in temp a degree & 1/2 or 2, then drop down to normal. Mine didn't seem to relate to flares or anything else I could point my finger to/at. It's possible that I've experienced minor 'secondary' or 'tertiary' infections due to the immuno suppressors I'm on, or that inflamation of the digestive system is causing these, esp. since it is most active during the evenings. I have seen me feeling perishingly cold while sweating bullets the size of gumboots. I would suggest a journal/diary of everything your son does, eats, drinks, etc.. with a specific timetable, to see if you can correlate it to the fever. I was never able to, and I just came to accept it, but every case is a little different, and such diligence might put you onto the trigger for these fevers.