Health care in the US is VERY expensive, hence why it is essential that everyone in your party has
travel insurance. We have, unfortunately, had to use doctors and hospitals on several of our trips over. But it is very easy.
You can either get in touch through your hotel or tour rep, to a local doctor, or pop into one of the Walk In Medical Centres over there - I know of one in LBV in Orlando, near the IHop at Xroads.
Make sure you have a credit card because you do have to pay for these walk-in clinics, around $90 for a straightforward exam seems to be the norm. Medication on prescription is much more expensive than we're used to - we seem to have paid around $45+ for antibiotics over the years.
Don't worry - everything works very smoothly. If, god forbid, you were to need emergency treatment (we have when DD on our first trip couldn't breath with croup), the hospitals are very friendly, caring and welcoming. Given it was very early in the morning, we had no documentation on us, but they were happy for us to get Katie treated and then ring with our insurance details later. We didn't even have the thought to ring our travel insurance people because we were so concerned about Katie, everything else went out of her minds!