Hi Dr Kara,
Thought you and future readers may want to know what happened with Iddy Bit.
You were right, the ER vet said that her coloring, despite covering her entire gum and palate area, is simply pigmentation. Because her pigmentation is so extensive, he said we can gauge oxygenation levels, in the future, by looking at her tongue.
They twilight sedated her to look down her throat for any obstructions (our main concern), polyps, swelling, etc...
They found some swelling and based on her other symptoms, he thought she either had a virus or maybe swallowed a toxic bug. But overall, he felt she was stable and doing ok.
He gave her a shot of steroid for inflammation and sent us home with L-lysine HCL, which you also suggested, to give her twice / day. We are giving this, preventatively, to our other 3 cats as well since they live in close quarters.
Today, she is much, much better. She's very quiet, not her usual vocal self but her purring seems mostly back to normal with none of her other previous symptoms. Plus she's back to her normal eating habits.
We were extremely relieved for her diagnosis and really appreciate your quick responses and excellent advice.
Thank you and keep up the good work!