Re: Lentils ?
I'm skinny as well and have never been able to put on weight. That shouldn't be a real concern unless you are deathly skinny. Try to work on the symptoms... Do you have a problem with gluten? I think everyone does to some degree so just make sure the oats you're eating are gluten-free. A lot of Oats on the market have cross contamination.
I would look into oxalates and perhaps going on a low oxalate diet for 2 weeks to see if you feel any changes. If oxalates are an issue you should feel something within 2 weeks.. like old symptoms might come back worse than before, you might have joint pain, urinary symptoms...headaches...etc. The symptoms are what's called oxalate dumping and will be pretty obvious
It seems your diet has a few foods I would expect to find in a 3rd stage candida diet...namely mangos and carrots. Perhaps too much of those might be causing some issues but it sounds like there's a bigger issue going on.
Just wondering before I throw any more advice at ya, but have you done a strict diet before? restricting all gluten, sugar, and all fruits for a while? do you have white coating on your tongue? Are you getting enough fiber? 30g? Literally count 'em up and let me know roughly how much fiber you're getting