The pup will cry out as if in pain. It will jerk its head up and straightn its legs out. It doesnt do this all of the time. But, I have also noticed that she is now breathing different. She seems to have a hard time breathing at times. The mom and the littermates have shunned her. She will crawl into a corner of the box away from them. Since my post, I have been doing some research on the web and I am afraid that she may be going through fading puppy syndrome.
I don't think she has colic, I think something may be wrong with her honestly. There are dozens of little reasons that puppies get sick and die. One of them is inticiception (spelling) which can happen from hunger or obstruction, rare in tiny puppies but it happens.
With mom shunning her, I'd get worried. Pull her, put her on a heating pad, make sure she is warm. If she is not warm and has food in her system she is going to have problems. Get her warmed up, check her hydration, and see where you are from there. The head tossing and leg kicking reminds me of my puppy that crashed at 3 days of age. She just needed to be warmed back up an drehydrated. Pinch her skin and see if it sticks or if it falls back to the body. Press your lips to her belly, she should be warm, not hot and not cool.
When I pinch her skin, it does fall back to her body. When I pressed my lips to her belly, it was cool. I do not have a heating pad so, I have wrapped her in a baby blanket. I have been trying to bottle feed but, I havent had much luck. She doesnt seem interested. My vet told me to force feed her. I am so scared that she in not going to make it. She turned a week old today.
She needs to be warm. Find a twenty four hour warlmart, cvs, whatever you have and get a heating pad. microwave some towels, get a water bottle, she needs to be warm. She can NOT eat when she is cold, that will make things worse. A baby blanket will not help, she can not control her body temp so she will only remain as warm as the room and blanket are. You have to provide some type of heat source for her. Put her in your bra if that is the warmest place if you have no heating pad or water bottles.
Do not attempt to make her eat until she is warm and comfrotable.