I agree this is also a possibility.Incredible record keeping of your sweet Cha Cha’s health and care. Kudos for being so thorough!
I really hope I’m wrong in my assessment, but my experience with a hen diagnosed with EYP and had almost identical poop actually turned out to be ovarian cancer. It created a blockage in her intestines which caused digestive issues similar to what you’re experiencing. However, once our girl stopped laying (she was only 8 months old), she passed less than a month later. So Cha Cha has already exceeded that and, fingers crossed, will make a full recovery. I wish you & your girl all the best