Oh my goodness Sherry, how awful for you. It does sound like there is something quirky going on in your car's innards.Hope they find out what!
The other day my husband and I were coming back from a medical appointment when a car seemed to fall from the sky. There was no engine noise, just a clunk, followed by a roll over clunk.
I still don't know what happened...leaving car in gear...maybe not. Reverse parking and driving too far is plausible. The car actually fell about two meters over a small fence.
The thing is, this was a seriously busy road,ut he was lucky, as were you.
Hope you are feeling better. :)