Contact your local Independent Living Center (ILC) -- they will be able to help you get a grant towards the cost of constructing a ramp or purchasing a pre-fab one. They may also be able to suggest providers or contractors for you to obtain quotes from.
It sounds like you need more help than just the ramp, though! There should be one or more organizations in your area dedicated to helping victims of domestic violence; in most states calling 211 (or using 211.org) can get you contact info for these types of organizations, as well as for ILC contact info, actually.
You should also talk to your doctor about your difficulties. It may be possible for you to receive CNA / personal aide / homemaker / companion services. In my state (Connecticut) and some others, there is a Personal Care Attendant Waiver program which both gets you the help with Activities of Daily Living (ADLs) your disability interferes with and, for many people, also makes you eligible for Medicaid! I am also on SSDI but not SSI (fortunately I'm past that ridiculous 2-year Medicare wait) and before getting on the PCA Waiver was in "spend-down" status for Medicaid, i.e. I had to pay over $3,000 in one year before I became eligible for Medicaid and even then it went away again at the end of the calendar year! But now that I'm on the Waiver program, I get 20+ hours a week help with errands, transportation, hands-on care & just about anything else I need, and I now have full Medicaid coverage to supplement my Medicare & cover most of the premiums. It can be hard to find info about these programs -- there are never as many waiting list slots as people who need the help, and some states don't have even a 'pilot' program yet -- but the ILC is a good place to start.
By the way, if like me you're within reasonable distance from two or more ILCs, don't hesitate to contact both for information & then decide which one (if any) you want to request actual services, like grant assistance for a ramp, from. There's often a significant variance in the helpfulness, professionalism etc. from one office to another.
BEST of luck to you, and stay strong!
--Jackie
