I don't know how normal it is, but I do know that my radiation ended at the very beginning of June and I had a very painful tongue through mid-September. Part of it, it turned out, was my tongue was swollen and rubbing sgainst some sharp teeth edges--when tehe dentist filed those teeth down just a little that helped a lot.

But I still have tongue pain sometimes, though not nearly as badly. Either when my mouth gets very dry or certain things, like something minty that would makes someone else's mouth feel tingly, will actually sting on one spot on my tongue.

I've had a few follow-up exams with my ENT and he's been very careful to look at the left side especially (which is also where I had cancer) and all he sees is some scar tissue. Also I've had a follow-up MRI and PET scan and he says these don't show any signs of new cancer. So even though I do get worried when I have some pain, I can say it isn't always a sign of recurrence. Still, I think if your family memebr is worried she should called her ENT and ask for her or him to look at the tongue, just to be safe.