Redness around anus

I have a 9-month-old kitten. We switched his food too quickly and he developed diarrhea so we called the vet.  While we've been treating the kitty for that, he has been scooting on his rear end often.  Today our cleaning lady, left a container of bleach cleaner (not straight bleach) that was almost empty open in our sunroom. While she was cleaning the rest of the house, she put our puppy and kitten out there. Since I wasn't there, all I can surmise is that the puppy knocked the container over and a bit of it got on the floor. When I got home and went to find my animals, I noticed kitty's tail smelled of bleach. His butt is very red but no blisters. Our vet was already gone for the day but I rinsed his tail area with warm plain water and inspected it. I think it just irritated that area more but it does look like he's missing some hair down there.  We live in a very rural area so we do not have an emergency vet.  He's surprisingly docile but I know he's in pain if he has to use the litter which makes me think he may start going outside his box. He has been drinking water but no eat except a couple pieces off my hand.  Any thoughts. I called my vet's home (I know bad) but I haven't gotten a call back.

Oh dear!  I don't know what you can do except wait for the vet.  Please let us know what they say.

I will. He's asleep on my lap now. I feel so badly for him. Poor kitty. 

Hi, do you have any cat shampoo?  I would definitely wash the area you think the bleach cleaner got on, and also wash the pads on his paws in case he stepped in it and then rinse very well.   In lieu of cat shampoo, you can use Dawn blue dishwashing liquid, which is used in wildlife rescue.  According to Vetinfo online, Dawn is safe to use to shampoo cats to remove oils, etc.  I would want something more than warm water to remove that cleaner from his coat and skin.

Scooting on the carpet sounds like worms to me, but he could have been doing it due to irritation from the diarrhea.  Treatment for that can wait until this is taken care of.  I think it's great that you called your vet at home.  Please keep us posted.  Saying a prayer for the little guy.