Yellow tongue for months can’t find answer

[Tmanshazzam]

So my tongue has had this yellow sometimes even orange color to it and it’s been like this for months. Sometimes there is like thicker white on the taste buds in the back of my tongue and the front there it just goes to the yellow/orange color. It’s usually not a thick coating or anything and when I brush my tongue or use a tongue scraper it won’t completely go away, almost as if it’s stained that color? However it does come and go, some days it acts up and others it does. I can tell when it’s acting up too because I get this sour/metallic taste in my mouth, I have also noticed things sodas and high surface stuff makes it act up. I’ve been to my primary doc and he had no answers and told me to see and ENT. I saw the ENT and I told do you think it’s fungal? And he said no and asked me if I’ve had any stomach issues lately which I have due to stress. So he chalked it up to being related to that and gave me a proton inhibitor to take for a month. I’m more than halfway through it and ya my stomach is better but the tongue hasn’t changed a bit...any ideas?