Hi, L & T. I hate to tell you, but undetermined fever seems to come with the territory! It can pop up out of nowhere. We'd try to keep track of where John has been and who he has been around to rule out "flu bugs, colds, etc." But often noone has a clue why he is running the temp. I do hope you can get the apartment arranged because, altho being away from home is hard, you both are going to need rest. Amy in the Ozarks