Foster kitten wound? Please respond!?

I am fostering four 6-week old grey tiger kittens for the SPCA. Two of them are on antibiotics for cuts but I noticed that another one of them had a dime-sized cut under his ear when I took him home. He was wearing a tag around his neck and it was covering it up, but the next day, I noticed the cut was gone, and there was a hole where it had been. It was not bleeding, and nothing was oozing out, but it was pretty deep and it looked pretty clean around the edges. It looked like there was mucus at the bottom, and I couldn't see any worms. I put neosporin on the cut and wrapped it with gauze but the gauze couldn't cover it fully since it was at such a strange spot on his head. I am visiting the vet tomorrow, but I want to know what I should do now. When I took him home, he was snuggling a lot and just wanted to be by me, unlike the others. I'm not sure if this is just his personality, or if the cut was painful and it made him lethargic. He is playing and wrestling a lot more now with his brothers and sister and I don't want his wound to get infected or hurt. Please let me know what I should do! I've done some research and all I couldn't find anything that seemed to match my description. Thank you all soo much! :)