Biting Cocker Spaniel -- Please Help!!!!

This is bad, but I haven't been able to take Penny to the vet yet.  My leg has been causing me so much pain and is so swollen that I had to cancel her appointments.  I missed 3 days at work last week because of leg. 
 
Right now she is acting like her normal, happy self and that is even when I am grooming her.  I have been grooming her more often to see how she will react and to let her know that even though she growled and snapped, she was still low dog on the totem pole. 
 
I have also been making her work for everything and and she is giving me no problems except for one.  When I let her inside from going potty outside I make her sit and stay until I get in living room and sit down and then I release her.  She is fine as long as I am facing her, but if I turn my back (even if I keep saying stay) she thinks she is released and comes bounding in. 
 
Anyone know how to keep her staying without me having to walk backwards? 
 
 

A dog needs about 75-100 repetitions of each behavior with the cue before you even think she's confirmed in it, and every time you change the "picture", the dog thinks the behavior you want from them is different.
Try teaching this in the house at first.  Turn your back only for a millisecond, then reward her for the stay.  Very gradually increase the time your back is turned.  Then, start going away from her a step at a time with your back to her.  Return quickly each time and reward the "good stay".  Once she's confirmed in the house, then take it outdoors (and you may have to backtrack to only turning your back for a second).  Every time you raise the level of difficulty, lower the criteria for which the dog is rewarded at first.

Thank you Spiritdogs, I will try that.  Penny learned the stay quite easily and she really will sit and stay for quite a long time so I thought I wouldn't have a problem with turning my back on her.  LOL most of the time when I turned my back on her she would beat me to the chair.  Once I almost sat on her because I didn't expect her to be there.