So update on Ollie!!
Ollie is doing monumentally better. It turns out, after keeping him under observation for a few hours, he started exhibiting classic snuffles symptoms. So, we treated him with a low-grade antibiotic along with yogurt, syringe-fed him water every few hours, and kept him separate from the others.
After a few days, he began to eat! Now he's running around and growing his hair back!