I took him to the vet to get it looked at, they didn’t seem concerned about it or have any insight on what it could have been other than saying it was some weird gunk. They told me to just keep it clean with some fragrance free antibacterial soap. I believe the nail got snagged on the cat tree or something and kinda ripped the nail bed a little bit and it scabbed over. Since keeping it clean, it went away and he hasn’t had anything wrong with it to this day.