It sounds as if your babies most likely have earmites. Have you observed them shaking their heads or pawing at their ears? This is easily treated with drops that your Vet will prescribe to you. Please do not attempt to clean their ears, as with such tiny babies, one little slip could damage their ears or push the substance deeper into their ears. Please get your babies to the Vet to be examined as soon as possible, and please do keep us updated how your little ones are doing!