Possible mastitis in my dog?

My dog has 14 puppies she is a doberman rottweiler cross. she gave birth to them all fine unfortunatley one was undevelopped and was still born. she has been nursing for 10 days now without a problem but we noticed the 2 closest to her bum are brown in colour and the ends are whitish and dry, starting to crack! Milk does come out and it looks normal we have been cleaning them with salty warm water to try soothe it. she doesnt retaliate or whelp wen we touch them. any thoughts on if it might be mastitis?