Hi there... I agree it is early for a scan and may cause unnecessary stress as they often light up due to healing... the usual is 3 mos post treatment. The white stuff on her tongue... try getting her a waterpik... they have one that has a blue end that looks like a spoon... on the lowest setting using lukewarm water... tell her to use it and scrape at the tongue gently. It may very well be a build up of guck sitting on her tongue (hence the sour taste I'm assuming this is on top of her tongue not under it since it likely involves taste buds)- if her tongue is sore as well (where the white is) then it may be thrush. Cutting down on sugar in take and possibly a prescription of nystatin will help. best of luck... hopefully it's nothing too serious. A lot of us have oral issues post treatment. Chances are because of your wife's age, the chemo, etc... her immune system is compromised and she will heal slowly. usually the first two weeks post treatment are the worst, she should be beginning to get a little better day by day. But a little over a month out it's not surprising she's having these issues. try not to worry. take care.