My dad is 74 has no appetite, when he does eat he either has diahrea or cold sweats. For the past 7 days he did not eat but drank 3 Dr Peppers a day for 5 days yesterday he ate some ice cream got diahrea then today had a fried chicken thigh and half of a baked paotato, and got the cold sweats. What is wrong with him? His previous diagnosis 6 months ago was prostate cancer and he has conjestive heart failure