Anxiety at its worst

I went to the hospital twice so far within the past month over anxiety and convincing myself that i’m having a heart attack. The first time i went everyone was really nice and stuff and i had a bunch of tests done to see if anything was wrong and nothing was but the second time i went was 2 weeks away from the first one and this one doctor treated me so oddly. She acted like I was stupid for thinking something was seriously wrong. I’m still going through these spells and i don’t know at all how to stop them. Does anybody have any sort of advice?