Is 50 for the lower number too low

What is the complete dyastolic and systolic reading?

I am not a doctor, nor a professional in health care.
I do know some people who have 70 as a lower number, and it's normal for them.
I would see a doctor, and find out for sure. If you can't afford a doctor, there might be a free clinic in your area. There are free clinics in many areas in VA. Good luck.