I agree - oils and intestinal flora (probiotics). I think a really strong digestive enzyme supplement would help, too, so things don't just sit there.
I would go to see a naturopath. They can recommend specific herbs to help stimulate your digestion and elimination. I used to have chronic constipation and food sensitivities but now I can eat almost anything I like, and am not constipated. So there IS hope.
You can also eat coconut oil (NOT coconut milk) and ghee (clarified butter).
Have you had your thyroid checked?