According to your mother sign and symptom and medical history she is suffering from peripheral neuropathy like motor or sensory neuropathy .
Reason- can be due to deficiency of
vitamin B12 and D with other deficiency.
You should do some test like CBC ESR and
Vitamin D and Vitamin B12 and
Calcium and
LFT and
Lipid Profile.
Problem in the vein doesn't cause generally that type of pain.
Problem in the vein can cause deep vein thrombosis and that can cause pain but what is exact cause for that you should take consultation again.
Next Steps
You should do some test as above I have told you and
take consultation again with good doctor .
Your mother will be well definitely.
Health Tips
Please say these good step as
follow good life style as take plenty of fluid and take less spicy and fatty foods and do exercise regularly with yoga and meditation and
keep positive attitude to fight any disease and any problem of your life.