Wow, I am so sorry to read this about Bella
I hope she gets better very soon.
Just speaking from experience, I would make sure that the water is not too warm, just barely lukewarm. When their skin is irritated, warm water can make it worse. When Miko had his allergic reaction, I did not bathe him in warm water because when I did, it irritated him. The pink became pinker. Barely lukewarm water is more soothing than warm water.