Michelle, She may not feel she has any appetite until she is ready to get off the prescription pain meds. They are notorious for killing appetite.
I still have problems with my tongue, especially when my mouth gets very dry, feeling like it's too big for my mouth and hanging over my bottom teeth, etc. It's ironic since I have about 1/3 less tongue than I used to, but I think it has to do with nerve damage from radaition as well as having a very dry mouth (so my tongue actually does get swollen and I feel my tongue sticking to my teeth).
It sounds like she is having similar problems with her mouth getting very dry at night and that creating a sore tongue in the morning. Does she sleep with a hyumidifier at night? That helps me a little and I am thinking of getting another one and sleeping with two this winter when the air will be dryer. Also, she may want to try using the biotene gel or liquid--putting some in her mouth on the top of her tongue before she goes to sleep at night. I have found that helps as well. Also, if she tends to breathe with her mouth open when she sleeps, she may want to try those breathe-right nasal strips and see if that helps her since sleeping with one's mouth open can aggravate the dry/mouth and swollen painful tongue in the morning effect.
I know 12 weeks since IMRT seems like a long time but I am a year beyond that myself and I can tell you from this perspective that she still has a lot of healing to do and it will happen. Just very slowly sometimes! Hang in there, Michelle (and Mom)
Nelie