It sounds like he needs to get his immune system response down. From foods, this could start with the following:
- Eat only low glycemic index foods
- Stop eating Omega-6 fats (soy, corn, etc)
- Eat a lot more Omega-3 fats
- Eat a lot more antioxidant foods
Things he probably cant do well which could help:
- Exercise
- Sleep
Im saddened for him and his loved ones. That sounds quite torturous.
When it effects the digestive tract there is just certain foods you can eat. A diet of broth is not healthy and that is basically what Shannon can afford and consume.