Swollen spot?

Hello. First post.
When I woke up today my 5 month old kitten had a swollen lip that she didn't have when we went to bed.
It's at the corner of her mouth and is probably pea sized. It's the same color as the rest of her lip. It's swollen more on the inside than on the outside.
I'm taking her to the vet in the morning (it's 3:30am), to get her an appointment for spaying, and to check on this.
I just wanted to see if anyone knew what it was before I get to the vet.
Thanks

My guess would be a Rodent ulcer. They are somewhat common. I have had cats come down with them.

Dont freak out...they are not caused by a rodent bite. That is just what they are called.

I think it has something to do with something in the cats system. But your vet will give you all the info.

Good thing you are taking her in. They cleared up on my kitties with some meds.

It could also be acne or even swelling from hitting her lip on something while playing. If you feel like it, update with what the vet found.

My vet told me that she had apparently bit herself. She has a loose/broken tooth (a 'molar' it's pretty far back), and hopefully it'll fall out soon.
He gave me two medications for her; a pill - Prednisone 5mg (12 pills, 2 times a day for 3 days, 1 time a day for 3 days, 1 every other day for 3 days), and a liquid - Clavamox 15ml (1ml 2 times a day).
If the swelling doesn't go down or gets worse within 7 days, I have to take her back to get the tooth removed. It's a baby tooth, so it's not that big of a deal, but it's best to let it fall out on it's own (and less stressful for her and less stressful/expensive for me).
She got all her shots (never been to a vet before) and she got a pill for intestinal parasites.
She was pretty good at the vets. After we were in the exam room someone brought a noisy dog in, and it freaked her out a little. She hatedddd getting her temperature taken, though.
I have to take her back in 3 weeks to get her spayed, and a booster shot she needs.
It's not very easy to give her her meds, and she seems mad at me afterwards, when she normally sits with me and hang out, she stays away for an hour or two. But she needs them. She didn't get the whole ml of Clavamox this evening, she ended up splattering some of it all over me, then sneezing a lot. I think she must have been breathing when I squirted it in.
Is there an easier way to administer liquid meds or is it just going to be tough?