My cat (2 years, female) and kitten (6 months, female) had successfully bonded over the last 4 months. They would spend all their time grooming each other, cuddling, and playing.

It's been almost a week since my cat has started hissing at my kitten, out of the blue. She's also meowing more than usual and louder. She aggressively demands my attention as well. Won't stop meowing or grunting until I pick her up and give her pets. I'm not sure what this is about, since she used to be very affectionate and a lap cat before we got the kitten, but was quick to turn her affections away from me and towards the kitty.

They still groom each other and cuddle, but the occasional hissing has started worrying me. It's just hissing though, no fluffed up tails, no forward pointing whiskers. Just a hiss, followed by the kitten moving away from her.

Some things that have changed in this week:

1. My kitten has started teething.

2. The kitten's regular checkup revealed she has had ear worms from when she was a stray, which she probably gave to the cat. We're working on getting rid of them.

3. Cat and kitten have found two lizards in the house to chase after. The lizards are also adept at hiding, so the cats have not been able to catch them.

4. We've got a new pungent smell in the house from something that's happening next door.

I would appreciate any advice/insight. I do have some specific questions as well.

1. Would my cat harm the kitten? I need to go out for about 3 hours every day and usually leave them both open in the house.

2. Could my cat be in pain? Does this warrant blood work?

3. Do I need to re-do their introduction?

Thanks for any help!