Hyponatremia is a condition in which your blood level of sodium is abnormally low.
Sodium plays a key role in your body. It helps maintain normal blood pressure, supports the work of your nerves and muscles, and regulates your body's fluid balance.
Some of the common causes of hyponatremia include: a low salt diet, certain medications(antidepressants, water pills, blood pressure medications), kidney disease, and hormonal changes.
It sounds like your doctor has reviewed your medications and feels that your diet is the problem. Avoid drinking too much plain water can also be helpful. Your doctor should repeat the blood work within one month, and your blood pressure should be monitored closely.
I hope this answers your question.