I am very sorry to hear about your .Mom!
I am not a Dr.
Most anti-depressent/anti-anxiety meds do have side effects but normally go away after awhile, sometimes more than one week, depending on the patient, but they have been known to help a lot of people, some times it is all about getting the right medicine.
Blinky bill might be right, sometimes anxiety does this to people, I have seen this and if your .Mom will allow you in with her to see the dr you should go in with her, or try to talk to the dr on your own, although with the privacy act they might not say anything.
I am just sorry that you have to go through with this as their is soo much medication on the market. Another thing you might want to ask the dr is to try another med for awhile and give her something to go with it until her system gets used to it for example valium(low dose) as I used to be on an anti-anxiety med and that was the only way I could do it and their are other meds to besides valium that wil kind of calm you or calm the muscle spasms or the burning or pain or whatever the problem is. Then again like I said, I am not a dr, she might have other problems, such as arthritis or a neuro problem, it is good in a way that the dr is checking out the other possibilties.
All the best!