Hi,
I feel sorry to hear you are going through these trouble. One thing I like to mention here is, think positive and stay happy. Psychological factor with set of positive mindset and rock steady approach, that's what all are looking to get encouraged. I read many a posts and concluded that what you are experiencing is a part of common recovery cycle.
I'll be greatly appreciate if you can add a little signature to your profile. This allows readers to know little more about you. You can see signature examples here on thousands of post. Just make one that fits your profile (Age, Stage, Site of cancer,,etc). Whatever you feel comfortable.
Tips for eating & tongue soreness, I would say expert opinions (doctor for soreness and swallow therapist) will be better choices. Also look for dedicated forum here, there are thousands of post here, all you need is to narrow down search using search bar here. Please feel free to get back to this astonishing place for more info and answers. There are more experienced leaders here, to name a few, ChristineB, Davidcpa, Paul etc. I am sure they will get back to you with a truly better answer than I've offered you here today.

Good Luck n take care....