My cat just gave birth to 5 kittens less than 48 hours ago. Her nipple area has been swollen for about the same size throughout her pregnancy but some nipples are now more red and 2 have a slight ring of some sort blackish purple substance(is it just dirt?). Also her breathing is faster than it normaly should be. Should i be worried? What can i do if it is mastitis? Can i still prevent it? How?