Pain at the root of the thigh may occur after post-operative chemotherapy for colon cancer, and it is important to consider whether there is a possibility of metastasis of the disease, at which time you should go to the hospital for a detailed examination to clarify the condition and then treat it symptomatically, and whether it is metastatic or not, do not blindly use medication to treat it, as it will affect your health if not treated symptomatically.