Since your sure there aren't any more pups to deliver by previous x-ray, thats the first to rule out. It is normal for a new Mom to pant for a few days after whelping. As the pup nurses and natural hormone releases, the uterus will continue to contract back down to pre-whelp size. With these contractions, she will pant. However, to be on the safe and prudent side. Take her temperature, rectally. Be sure its in normal range..101-102 degrees. Make sure she doesn't have a foul smelling or green tinged discharge and any obvious signs of excess bleeding. Its worrisome that she isn't drinking...you can try putting half a teaspoon of sugar to 1 cup of water and offer it...if she isn't interested, try putting in a syringe and giving directly to her. If all is normal with temp, discharge right now and she refuses to drink by sun up, I would definately call your vet. New pups will sometimes be little yackers when Mom moves..They have a "startle" reflex that will cause them to cry with movement in the beginning....some are just louder than others
You did say the little boy is nursing fine, right?