Can a hospital refuse treatment?

I went to an emergency room on a Tues night with horrible pain in my sides they checked me in the dr saw me then in comes registration to tell me that the dr said I didn’t have an emergency so I either had to pay 400 bucks for deposit or they wouldn’t treat me I was like woa I don’t have $400 right now so I left I was way too exhausted to go to another hospital so I waited till the next day I went to another ER and they took me in asap..well to make things short, my so called “non-emergency” I ended up in ICU for 3days and 2 days in a regular room before they let me go home. I had infection in both my kidneys very low blood level to where they had to give me 4 blood transfusions & low blood pressure. Well since I was admitted to the hospital I started to wonder was that right me getting turned away it seemed to me like an emergency & to the 2nd hospital I went to! I’m just wondering, this just happened like 2 weeks ago I’m still really bothered about it!