What should I do if i went in for fluids at the hospital and they ran all kinds of tests? I dont have ins?

They didn't tell me. They were running all kinds of tests. I had been to the doctor earlier in the day and was told I have the stomach flu. Had to go to the e.r later in the day to get fluids. My doctor which is associated with the hospital called down to the ER to let them know I was comming in for fluids. They ran blood tests, urine tests and did another test for what reason I have no idea. Thinking it would cost around 500 dollars much to my surprise it was 1700 dollars. I called and they did the whole we did everything they need to do. I had the stomach flu I knew this from the appt in the morning. Is there anything else I can do to fight this bill?