Waking Up With Yellow Stuff in Mouth and Acid Feel

Hello, I wake up since longer time with yellow stuff in my mouth around teeths, and I don't know how to treat it. My mouth dosen't fell fully dry but acid full bad pH but mostly only aroud sleep. Could someone help me please? I'am trying to fall asleep with closed mouth but I don't know If I do. Also one of my teeth fallsapart I will see dentist and I avoid sugar to 90% but still... I eat dark chocolate, butte, I take vitamin D3+K2 drops, use Xylitol natural gums, started using black walnut drops, and did add Yesterday horsetail powder into my side toothpaste Bentonite clay+cinamon+horsetail. My main toothpaste is since half year a Xylitol and some other stuff and today I started doing oil pulling again. I hope I find some answers and I also eat pretty healthy and I'am vegetarian.