I'm having a panic attack. How can I relax? Please help?

I pulled an all-nighter last night, and I'm still up. I had a migraine this morning, so my mum gave me 2 Excedrin Migraines. I also had a red bull. I have a heart murmur, so I'm starting to panic because my heart is racing, I'm getting worried and I can't calm down. I'm only 14. What should I do to relax?