seborrheic dermatitis food intolerance ???

Hi everybody, here's my story:
I started to get Seborrheic Dermatitis 3-4 years ago. At the beginning, it was just on the scalp, then eyebrows and forehead, then nose, cheeks, ears torso. I saw 1week ago that the cause could be a yeast overgrowth and that the cause would be in the gut (since, that day, i thought that skin diseases were all there because of a problem in the skin...). I usually eat a balanced diet: lots a different fresh and raw vegetables, yogurt, fruits, meat, fish, healthy fats and quite a lot of grains (brown rice, oatmeal). When I did the spit Test for candida overgrowth, I immediately recognized the symptoms. So I started 5 days ago a diet where I don't eat grains, dairy, starchy vegetables and fruits, nor Sugar from anywhere else. My skin went better (not oily anymore, less-dried skin, no peeling anymore, reduction of redness, no itching on my face, just on the scalp) I started eating a carrot every two days and 1 apple every two days too and nothing bad happened. I've also started eating around 80gr-100gr of cheese with low (<0,5gr Sugar per 100gr) to no carbs and Sugar at all and nothing was bad either, if not a bit better. Then I tried yesterday to eat 1 serving of quinoa (as it is gluten-free) and I immediately get symptoms back (my skin went dry and peeling again, not smooth skin and a lil bit red too). I ate some coco-chocolate and milk chocolate 2 days ago and my skin did not have any problems nor my digestion. So Im wondering: is it possible that my yeast overgrowth and so Seborrheic Dermatitis come from grains (even gluten-free)? Is it healthy to remove ALL kind of grains from the diet in the long term ? I can eat sweet potatoes but where can i get my carbs elsewhere ? What should I do to cure my gut problem and have a balanced bacterial flora in the gut again ?

Thank you very much for your help, i am desperated !

Also, my SD disapeared this summer and i was able to eat tons of grains and A LOT of alcohol without having it back. But I think it went back in september cause i began to eat a lot of crap food in large quantities quite often (every 2-3 days, chocolate, nougat, icecreams, mars, snickers, chocolate biscuits...)
What do you think about that weird phenomenon ?
I add that in june i ate during 1 month vegetables, legumes, fruits, oatmeal and brown rice, no meat, no fish, no oils, no sugars or crap food.
I also took Antibiotics the last week of august but my symptoms went back around 10-15th of sept. Tweet