Worried opinions?

I got a kitten weeks ago 10 weeks old. I took him to the vet he got his first kitten shots his exam he had fleas so wasbathed and 2 days later I gave him revolution given by the vet. He was also checked for fiv/ felv and was neg.

I notice he drinks a lot if water his mouth is always wet but then I notice that around his mouth he has a thicker mucus discharge sometimes. He eats but seems skinny but he plays with my other kitten purrs and potty normally. I thought maybe teething but I've had many kittens in my life and never had them drool like this I checked his moth but didn't see anything no blood or anything.
I of course will be bringing him to the vet today I just wanted to know everyone's thoughts.

He definitely should not have mucus coming out of his mouth. Do let us know what the vet says. Glad you're going ASAP.

So he has an ulcer in his mouth vet gave him 2 weeks of antibiotics thinks it may be a virus. We will be keeping an eye on it.

How is your kitten?

He's doing great!!! He's now eating well and gained almost a pound!!! I feel so bad I didn't catch it sooner I just thought he was nervous and stressed so he was being fussy.

He now is great with all the other cats and the dogs too. He just went in for his second set of kitten shots and the vet said he looks good. He said he still has a little irritation on his tounge but it should go way.