I Was Told My Sodium Level Was Low, After A

I was told my sodium level was low, after a check- up three months ago. My blood was tested yagsin esterday, and it is even lower. 15. But, i know nothing about this.
I am told to stop the furosemide, 25 mg daily. And the Losartan. This is for blood pressure. My blood pressure is around 155. I take 2 metorolol a day, also. Should I increase that?
If I take the lasix, my blood pressure is easier to control. What causes low sodium? She said to not drink water. Just gator ade, broth and juice. Or green tea. I am 72. Disabled, with osteoarthritis, and osteoporosis.
What causes low sodium? Could this indicate a kidney problem? What could be my underlying cause?
Thank you and God bless you. Marian Gross