Mandy,
Is your husband taking pancreatic enzymes to help with digestion? If not, some of his pain may be gastric distress from being unable to digest the food he takes in. It's important to take the enzymes post Whipple surgery, and to take enough of them to control symptoms. Believe me, the pain from undigested food passing through you system can be severe and not always confined to your abdomen. Pain medications will not alleviate this, and it can last for hours after eating.
After surgery, my stomach was very sensitive to spicy or rich food. This lasted a few months. I was prescribed Nexium to reduce stomach acid, both to help with the sensitive stomach, and to reduce possibility of stomach acid causing ulcers on the reconstructed stomach tissue. It helped me a lot. I was able to gradually return to eating foods I enjoyed.
Food is an issue for most people after Whipple surgery. I didn't have much of an appetite. But I was told how very important it is to eat a well balanced diet, low in fat, and to include protein in every meal. They wanted me to consume animal protein in minimum one meal each day. If your husband has been eating only cookies for 9 months, it is most likely contributing to his weakness. I agree with you, it is odd that his doctors are not concerned.
From you message, it sounds like your husband it seriously depressed. From what I have read, depression is a very common in patients with PC. Dealing with both the illness and the Whipple surgery is a big challenge. Maybe your doctor can give your husband something to help with depression. Some of the PC patients on the John's Hopkins PC forum say the depression/anti-anxiety meds made a huge difference in quality of life, and helped with their appetite and in some cases, pain management as well.
I'm not in the medical profession, just a PC survivor and the things I mentioned, other than depression, are based on my personal experience. I'm sorry for your husband's difficulties and I hope he is able to get some help soon.