Hi Mary, the US health system is very complex and in some cases it could happen that you'll need to cough up a lot of -$$$-. Insurance companies in most western countries offer a US health insurance add-on on your holiday insurance. This could cost you up to $50 a month. I urge you to take this seriously because healthcare in the US is a very complex matter and doesn't work as simple as the UK NHS or Aussie Medicare.
You should have to be care with your health because is an important thing in our live, just in case, if you need any medicine you can buy it on-line and it's safe.