You could ask to try taking mirtazapine as it has been known to help a patient rapidly as appeared in a gastroenterology journal. It is a type of antidepressant, but it isn't given for depression for this problem. It has other actions. I don't usually suggest asking an MD for a rx, but for this problem it might be a good use, hopefully causing improvement and maybe not needed for the rest of your life. But it is important to get good nutrition for your brain health and bones and preventing cancer.
You might try L-glutamine as it is a supplement that helped improve absorption for me when I was recovering from Celiac damage to my intestines. It is the only thing that turned things around and helped me gain weight.