Adenocarcinoma (Colorectal) Stage4. Too.

My mother is undergoing chemotherapy (6 cycles complete) and targeted therapy (3 doses complete). During her 6th cycle, she experienced extreme pain due to constipation which wad relieved after enema and NS. But the mild pain continued even after stool passage. After the completion of 6th cycle, she again experienced constipation and with the immense pain this time. Though she is getting the flatus. We headed to emergency at Hospital, and they gave enema but she didn't get stool. Doctors have asked to keep her on liquid diet mentioning that there is no blockage in large intestine but small intestine which can only be relieved after high consumption of fluids. I would like to ask that how I can relieve her pain. Pain is in batches, when occurs its intolerable otherwise she is fine. Also she has not passed stool yet. Please help. She is diabetic too.