Help W/ Medical Expenses Traveling

I have a cancer issue that has been treated locally, but now they want me to go to a clinical testing clinic in Florida where I have been seen and
treated previously.

Once I get there, my expenses are covered, but I don't have the funds to make the trip from Michigan to Florida and (hopefully) back.  All I need is traveling funds. My car gets roughly 23 mpg and the trip is about 1600 miles long each way.  It works out to roughly $400 for fuel round trip. Having been a  long time traveler, I know that it is not wise to leave with a margin of a couple of nickels.