Burning & Numbness in foot

My 80 yr old mother is experiencing numbness or tight feeling in her calf down to the toes of one foot along with sharp pains occasionally to the second or third toe.
She also says there is a burning sensation as well.
The dr. has checked her and says her circulation is fine.
Is there other tests that she should ask the dr. to do?
She does have congestive heart failure.
Thank you.