how can i be sure that i’m still alive

i had a bad heath scare 2 days ago where i had a panic attack but i thought i was having a heart attack even though i’m 18 and don’t have any underlying problems. i went to the er yesterday with my dad to find out and had 2 ekgs that were fine. i felt reassured but i was worried because they didn’t do the blood test to be 100% sure so i was super afraid all night that they missed it. i was super afraid to fall asleep because i thought i was going to die. i woke up(?) this morning and pinched myself immediately and then i think i picked a bad spot because i didn’t feel it but i do now. i was googling am i still alive and shit 😭 i’m still super freaked out especially since i’ve been home alone and i didn’t get called on or acknowledged my entire zoom class this morning. i know i’m alive but also like what if i’m not. has anyone experienced this before? is there any way you overcame it quick? i’m just so freaked out and i feel super alone and crazy right now