When you give him his soak later just let him sit there abit longer then usual and he should be fine from Neosporin, I would imagine your not putting huge amounts on and if it was really bugging him or effecting him he probably wouldn't be still eating and stuff. Just discontinue use till you get the other one. And don't be hard on yourself, everyone makes mistakes in the beginning that's part of the learning process. Breeders have probably made tons of errors to get were they are and learn what they know so even the best make them. So just keep quarantined, get the other Neosporin and keep doing the other things till Monday when you go see the vet. For all you know it may not be redleg at all and some mild bacterial infection or something in which antibiotics would be needed for anyway. If things get worse like he stops eating or moveing let us know and if not on monday let us know what the vet says.