My parents are threatening to take me to a mental hospital help?

I have been under alot of stress for the past 3 weeks. i recently started having really weird heart problems. My heart beats very oddly instead of going badum badum badum it goes badum dum dum badumdumdum badum badum i am really scared . i told my parents and they said its all in my head because i have anxiety and nothign is wrong with me. my mom said she shud just take me to a mental hopsital cuz none of them can take my "sh*t" anymore. please someone help i just turned 18