In response to your question, "Were anyone else's mental problems helped by going on SCD/GAPS diet",
Yes, yes, and yes. But everyone is different, so you may have to tweak. There IS a brain-bowel connection and a healthy gut helps a healthy liver and a healthy brain/mind. When those things are in order, you'll be more alive, energetic, alert, positive, and grow self-esteem and confidence a lot quicker.
Keep working at it and keep fighting. "Restricted" diets really aren't restricted at all, There are TONS of foods you can eat while avoiding others.
If you want, the SAD is more "restricted" - they just avoid all raw/pure/organic vegetables, leafy greens, whole-food sources.
Cut out the crap, but for you, that might mean something different. I was all about Primal a couple weeks ago (trying to heal my own digestive troubles and correlated emotional turmoil) but I'm already vacillating to a more asian/vegetarian approach. We're all learning. If you're finding Atkins doesn't work for you, by all means, try something else. Keep reading......