Isn't McDougall a very low fat diet?
Seems to me that part of your problem on McDougall, is that you are simply not eating enough fat.
I got the impression from your posts that you oscillate between an all meat diet which made you feel best and a McDougall diet (which i understand to be vegetarian, low-fat), which you liked best.
I'm not surprised you are having problems. I don't think I could do it either. Even when hungry, I am not especially attracted to meat. I'm fine with meat along side my salad, or vegs, or cooked in a stew, but on its own? Bleh.
I think maybe you need to stop the extremes. Do a sort of addition (as opposed to elimination) diet. Start with meat, which you know you tolerate well, but do not especially like. Add things back gradually and see how you tolerate them. Add food one at a time, and monitor yourself for any reactions. Keep a strict food journal.
The food that are most commonly allergenic are grain containing glutens, milk, eggs, nuts (especially peanuts).
Make sure to eat lots of good fat (satured and mono). I think that your hunger on McDougall was due to the effect of all those carbs on your blood sugar, unmitigated by any fat.
BTW, your symptoms sounds a lot like hypoglycemia.
As for your gut issues, you are obviously intolerant to a few things. Take a lot at this series, it's very interesting
http://perfecthealthdiet.com/?p=235