numbness in pelvic area down to feet

Hi, I have had numbness in my legs for the past year. Initially the pain was from a cancerous tumor in my pelvic area which pressed on my sciatic nerve. I have started chemo and the pain is gone but now I have constant numbness with no feeling in my pelvic area, with no bowel control. I have a colostomy bag due to the tumor obstructing my small intestine. If I spend too much time walking around my feet get really cold and even more numb. I also experience sharp shooting pain in my feet, legs and pelvic area. Not all the time but daily. Is there anything you can tell me to help?