Please help

I feel like I'm dying so bad right now and its scaring me so bad. I was just sick and decided I should try to do my theatre performance since I felt better but as soon as I got there I started overheating and feeling like I was gonna faint. Fainting is one of my biggest fears so I was freaking out so bad I had to go home after already getting ready for the show. Its been hours and I still feel like death. I feel weak, sweaty, not real, insanely tired, and much more. I don't even remember the last time I felt so bad. I just feel like soon enough I'm going to die. How do I calm myself down? its been like 6 hours and I can't stop worrying. This is almost the worst its ever been and idk if Im going to ever get back to normal I can't even fall asleep like I usually do when I feel super anxious.