Chemo often caises deficiencies in iron and potasium, both of which can contribute to fatigue. If you get enemic they will give you injections that can cost thousands. Often the injections end up no longer working, if it's an iron deficiency this means a blood transfusion, In the case of potasium, unless you have a port, the infusion itself can be painful. I found daily supplements bought at the pharmacy stopped both of these problems, 58 mg of iron daily and 99 mg of potasium daily. Digestion can get messed up. I recommend taking the enzyme acidolpholus, preferably naturally in yogurt or milk. You have to read the labels to make sure it is included. If your dad can't do that, there are also acidolpholus supplements that can be taken (remember to refrigerate after opening). Chemo effects digestion in many different ways. To eliminate discomfort have Immodium, laxatives and stool softners available.
Most people avoid spicy food and prefer a bland diet. I printed up daily menus on the computer with a wide variety of options including drinks and deserts. I also found I had more success getting my partner to eat if I provided small portions of each item. Usually I would get requests for seconds. With large plates of food, they were often pushed away without a thought...too much food to imagine eating. Also, with small portions you can offer more variety to provide a wider variety of nutrients.
Good luck and god bless.