How does one find out if they are eligible for social security benefits?

I am 52 and have severe arthritis in my knees and back that keep me from standing or walking for more than a few minutes at a time. I used to be a truck driver (Almost 15 years total) but have high blood pressure and vision loss that prevent me from passing the DOT physical. I haven't been able to find any other work that can support. I have been almost getting by on money made from handyman work and borrowing from family but things are just getting worse every month.