Mom's cancer fight

My mother is diagnose with stage 4 Esophageal cancer in February 2013. When she diagnosed she had 4-5 mets in her liver and multiple mets in her spleen. She didnt have any problem with the swallowing or appetite. And she didnt have any weight loss when she was diagnosed. after this time she had 6 cycle of Chemo with carboplatin and taxol and responded it very well. After the 6th cycle there was only one 8 mm met in her liveran one 10mm in her spleen . she had a 4 months chemo break untill november. But the scans in nowember showed a great numbers of liver mets . metastatic liver involvement but the met in spleen was stable still. She started weekly chemo with cisplatin , gemcitabine and dexamethasone. Now she is having this coctail for about 2 month. She is goning to have pet scans next week . Im very worried and excited. Because she has still no waight loss, appetite loss, no swalling problem. But she has difficulty and sometimes joint pain in her liver area, and she has a very swelling abdomen, constipation, nausea. She still works, cooks, has a good mood, and doesnt lokks like a cancer patient at all, Im worried whats the reason of her difficulty in her abdomen . is this the invasion of cancer or side effect of chemotherapy?