We received a new kitten about 6 weeks ago...He is know about 13 weeks old. He got outside about 10 days ago and was under my boyfriends truck. when I got from underneath the truck he had grease on his fur. so I washed it off best i could with dawn dish soap. i noticed that evening it was still on him so I washed him off really well with just water. I read online to try baby powder and that seem to help. Now i've noticed that the whole area is kinda of a yellow crust....Is there anything I might be able to do without bring him to the vet??