Losing faith in God

Hello, i’m 15M. Since i was a kid, i didn’t believe in god and just sinned many times. Then, maybe 1 times 2 years ago, i turned to god, tried to stop sinning and i actually made some improvements, i stopped saying curse words, i decreased my lust and did everything i could, until february of this year, started having some physical symptoms and i thought i had heart problems, did all the check ups and 1 month ago it became much worse that it got debilitating, i cane enjoy anything, i only think about that i’m dying and i could die at any moment. To be fully honest, i never prayed everyday, i prayed when i felt like too and during this time i prayed many times. I can’t sleep i cant do anything. I want to enjoy summer, i want to do everything a teenager should, not having these constant symptoms and worrying about death. I’m so exhausted and these feeling are slowly turning into anger i cant control and i shouldnt say this but this anger is also against God like why would you do this to a normal 15 years old who believed in you while i know some people that literally mock God in so many times and they live their best life. I lost all hope in everything, even in God