Hmm this either means 2 things none of them good
Firstly the chemotherapy has damaged his intestines possibly causing them to perforate. Chemotherapy would damage the intestinal lining as the cells are rapidly dividing cells ones which chemotherapy targets depending on the severity he could completely recover with a minor resection or worst case be left with a stoma
Secondly the worst case scenario the cancer has metastasized to the intestine or the very chemotherapy itself has caused these cells to mutate.
This really doesn't sound good for Tito the body can only take so much punishment from chemotherapy before it begins to break down hoping it's not as serious as it sounds