Stephanie- your post is one that most of us are hesitant to answer because there could be any number of things going on. Some of what you described happened to my husband on many occasions- undetermined fever[ along with chills] and headaches. Some of those episodes were attributed to the chemo, some were attributed to "picking us a virus", some were never diagnosed. If he hasn't been around "sick people", it could well be a reaction to one of the chemo drugs he is on. Hate to tell you, but welcome to the world of "not knowing for sure what the heck is happening". There will be many days it takes nerves of steel to be a caregiver. Get yourself prepared. Amy in the Ozarks