Marvin had a rough time when he would get constipated also. We would not be able to get all of his food down. He would also break out in a sweat and was in alot of pain. We have found out that the extra fluids given him during his chemo helped. We have found a solution that seems to be working for him. We put 8 to 16 oz of prune juice in the tube plus he takes milk a mag. I also try to make sure he gets at least 64oz of water each day. Marvin only has 3 more rad treatments to go. Hang in there. Good luck