Left sided chest pain can be due to any of the following reason:
Considering your mother's age, past and current medical condition, any family history, the physician will have to do a complete general and physical examination of her with regards to vital parameters of body like Blood pressure, pulse rate, respiratory rate, and heart auscultation etc.
Following can be the reason of chest pain:
1) Cardiac disease (heart disease) -
If she has any other symptoms other than chest pain like difficult breathing at rest or exertion or excessive sweating or palpitation (meaning increased heart rate which patient is able to hear herself) etc.
Then we require to consult cardiologist and following test needs to be performed
1) ECG
2)
Lipid profile- serum cholesterol, VLDL,
HDL,
triglycerides etc.
3) Cardiac enzymes marker- Serum troponin I,
creatinine phosphokinase, LDH.
2) Gastric pain (retrostenal gastric or stomach pain)
If your mother has this chest pain with respect to timing of food eating habits or pain is after eating meals or when she is fasting.
Then it could be pain due to hyperacidity which we call (gastro-oesophageal reflux disease)
3) Muscular or joint pain-
If your mother has pin point pain at bony junctions of ribs it could be costochronditis or osteochronditis.
It can be easily dealt with medicine.
So, it will be better if you show your mother to some MD speciality in internal medicine or MD medicine.