Kitten with diarrhea?

6 months old male kitten. Started having diarrhea last night. But it's not typical diarrhea, it was actively oozing out of his bum as he's walking, sleeping...doing anything (sorry for the gross description).

it was very late when I noticed it, he was moving, playing and sleeping all normal. I gave him a shower, everything seemed fine.

This morning I checked on him, nothing was there so I thought everything's good. Around 1pm it came back so I called the vet to take an appt and told them all the info. The vet advised to give him meals of bland rice and chicken and monitor his situation for a couple of days, if it stays like that then I can bring him in.

He, along with his two siblings, have been on the same diet (dry and wet meals) since I got them. Never had this issue, and his two siblings are perfectly fine right now. I was wondering if anyone has gone through this or something similar and have any advice?