Brown discharge is not normal from the vagina. I assume there is not a change this dog could be pregnant. This could be a sign of a pyometra--a uterine infection. This can become severe and life threatening. The milk from the nipples could be related to a mastitis, this can be secondary to a pseudo pregnancy. This dog needs to be examined by a veterinarian to diagnose this problem. She is panting and whimpering from pain and discomfort. Finding the problem and treating it will relieve her pain.
