Acting strange a month after giving birth

Question
My dog is 14 months old. She's 1/4 Rottweiler, 1/4 Lab, and the rest is unknown. She finally went into her first heat around November-ish. The neighbor's very large Brindle Pitbull broke through the fence and we didn't realize she was pregnant until the last 2 weeks of her pregnancy! She gave birth to 7 boys and 2 girls, all healthy on January 20, 2010. The pups are almost 4 weeks old now and she's slowly trying to wean them. Their teeth are in and their nails are sharp, so she shakes them off and paces the enclosure. She voluntarily goes in with them, but will quickly come back out and go back in after awhile, as if she wants to nurse them but it just hurts! I've started feeding them the same puppy food she eats which is Purina Puppy Chow, softened with warm water to try to give her a reprieve from them. She came in from outside tonight and immediately went to the pups. She gave me the most awful look when she was nursing the pups, so I let her out. She immediately went into my living room and laid down on some pillows. She's breathing fairly heavily and for awhile was whining on every breath. She's quite warm and was panting for awhile until she laid back down. She was uninterested in the dog food (which she has eaten since she was 8 1/2 weeks old) so I put a little warm water into it to soften it and some chunks of hot dog (her favorite). She gobbled it all down, including the dry dog food like nothing was wrong, drank some water, then went right back to her spot she picked out to go to sleep. I've noticed her nipples are a dark burgundy red, but figured it's just from the puppies swarming her. She also has been very skinny since giving birth. I know it takes awhile to gain back the weight, but she's so skinny and her spine sticks out a bit. I've been free feeding her since we realized she was pregnant, and for the most part she eats great (unless she's holding out for some chunks of meat). She doesn't seem to have worms, and none of the puppies have discharged any worms either. Any idea what could be causing her strange behavior?

Answer
Hi Kasey

Worms can lay dormant in the muscle until pregnancy.  I would be de-worming not just her put the pups too. It's a false sense of security thinking that the dogs don't have them.

9 is a big litter so it will take a bit for her to bounce back.  Did you notice if she expelled all the placenta's for each pup?  Anything retained will cause infection and fever.

With her kibble include a can of dog food, raw organ meats (heart, kidney, liver), also include a supplement such as Missing Link available at pet stores.  

Check her nipples to ensure they are not hard and hot. Mastitis is common in females and if they are painful you can stand her in a bath tub full of warm water and gently express them.  Also a balm rubbed into them will help keep them supple.

Finally, now that the dog next door has bred, he'll want to do it again and again whenever she comes into heat (which should be in another 3 - 4 months).  I would consider having her spayed once she is healthy.

Good luck