I have been having extreme low back pain for 3 weeks.It started with a sharp shooting pan in low back,later radiatinv down my legs,and for over a week, I have had extreme pressure in my bladder.Frequency to urinate,no blood,but pressure.I am 71 years old,and my mother had a strong history,and died at age 79 with pancreatic and liver cancer.I have lost 10lbs over a few months for no reason.What is it?