THREE WEEK OLD FEMALE PUP

Question
MY FEMALE HAD A LITTER OF ONLY TWO AND SADLY THE MALE DID NOT SURVIVE, LEAVING A VERY FAT AND BIG FEMALE.  SHE IS HAVING NOTICABLE DIFFICULTY STAYING UP ON HER HIND LEGS.  SHE HAS SLEPT ON HER SIDE OR HER BACK WITH MY SUPERVISION, BUT AM WORRIED THAT SHE ISN'T DEVELOPED WELL ENOUGH TO KEEP HER BACK LEGS IN CONTROL.  HER HIPS FEEL LIKE JELLY AND SPLAY OUT BEHIND HER AFTER ONLY A STEP OR TWO.

Answer
The mother should still be nursing...is she? the puppy is just learning to walk by 7-8 weeks the puppy should be fully weaned and able to eat and drink on its own plus walk and play like any other puppy. You can buy puppy milk replacement formula and mix and warm it and supplement her with it if you think her mother isnt feeding her often enough.