Also, you might consider using existing messaging app. Then you can interact if have them install the app. Matrix might work. I think Matrix can do SMS.
Does anyone still pay per text?
It makes much more sense outside the US than to pay for a text bundle. My phone plan includes 0 SMS messages, and I don't know what was the last time when I've had to send one was. It's only useful when someone doesn't have internet, which only happens once every few months at most.
"I was in a car accident, come to general hospital downtown"
I would have used two textboxes, Title and description, but this works as well.