One thing you must realize about so called doctors. they are agents for drug companies and will only treat and not cure anything like what you have.
I would recommend lots of cooked veggies like soups with beef, or chicken broth from the bones. One very important supplement you will need is L-Glutamine, a good quality brand that will rebuild the walls of the colon. I have been trying and using HCL because I have been very low on stomach acid, also my B12 absorption was poor. A new product I just ordered will soon be here to restart the fire in my digestive system something with Tibetian herbs and Chinese mushrooms. This will take time and if you have about 6 months to a year to devote to the correction it can be done. So far you are on the right track, you just need to make some minor adjustments.