Get the doctor to do a Lyme Disease test. It's worth a shot.
Sorry to keep adding--can't edit my posts. Ran across this case:
http://www.ispub.com/ostia/index.php?xmlFilePath=journals/ijn/vol2n1/vitamin.xml
Looks like the patient got more frequent b12 injections than your mom.
Glad to hear it if I have helped in any way. B-12 may not be the right answer, but your doctors will tell you, it's unlikely to do any harm; your body generally excretes any excess. The kind that melts under the tongue even tastes good! Just give it a few hours after food.
If you want some informative reading (but it's very technical, take your time) try this: http://www.neuro.wustl.edu/neuromuscular/time/nmacute.htm#neuropathy
There are lists of possible tests here: http://www.questdiagnostics.com/hcp/intguide/jsp/showintguidepage.jsp?fn=CAP_LabDiagnosis_PeripheralNeurop.htm and here: www.lizajane.org Most of those focus on causes other than b-12 deficiencies.
Good luck, and please report back.
One more thing:
I just noticed your mom has high cholesterol. Neuropathy is a known side effect of statin drugs in some people. Is she on one, like Lipitor? Do some research. I'm not aware that statin neuropathy is as severe or acute as you've described; I'm just throwing an idea out there.
Mayo Clinic admitted my Mom when she had her appt. with them. I did not realize it but there were still some tests outstanding. However, they all came back negitive. Once the doctor saw that, he made the decision to admit her and start a treatment consistant with her symptoms even though he has no diagnosis. I will keep you all posted as to her progress. I thank everyone who posted to this message for their help and support. It is much appreciated!
I have done some research on methylcolabamin b-12 and do believe that this the right way to go for my mothers symptoms. My sister will be speaking with the doctor tomorrow so I will have her ask him what kind she was given. Thanks for all the info you have given me. It has been a big help.