Litter of baby bunnies have patchy fur around ears, what should I do?

[Trin]

My litter of 6 baby bunnies is 4 weeks old, and they all have patchy fur around their ears and no fur on their feet or tails. I am a bunny breeder but I have never seen this before. I think it might be a fungal infection, but I am not sure how to get rid of it, does anyone know what I should do? I would prefer not to have to go to a vet if possible. Thanks, Trin!