Hello. I know it has been a while since you posted this, but I am wondering if you have had any resolution to this, and if so what it was.
I developed an orange tongue years ago and discovered after much digging and researching that it was likely due to an oral overgrowth of Acintomyces spp. bacteria. It went away after treatment with penicillin. I did develop issues with my digestive tract around the same time. Not sure if it was related or not, but I was eventually diagnosed with Small Intestinal Bacterial Overgrowth.
I just wanted to share my experience. I hope your orange tongue has resolved!