My mum suffers from sharp pain on the right side of her back and abdominal pain. The doctors can't tell what is wrong with her.?

Second opinion. There are many causes of back pain and abdominal pain together, so figuring out what is going on really does require thorough evaluation. Do not be afraid to seek a second opinion if you have concerns.
Good news. She has a doctor and they are trying! Likely they have tested out the most dangerous items! Keep, up the followup.