Can someone tell me what is wrong with me?

it all started in july i was getting ready to go out of time and i broke out so i thought it was melanoma. My cousin who is a nurse told me that it isn't. But i didn't believe him. So i searched on the interent and i thought i had melanoma. It took about a month for it to leave (it was probably eczema) I soon was sick with a cold. and my hearing was effected and everything sounded low. My cousin said that i was partially deaf. so i took it seriously was scared (i didnt know he was kidding.) so i was having headaches everyday and i thought it was a brain tumor or multiple sclerosis. cause i looked it up on the internet. then i keept on seeing flashes of light in my eye so i thought it was retinal detachment because the internet said that what it was. So i was tired and weak all the time and my head felt heavy so i thought i had leukemia. I got my eyes checked (they are both healthy) My body checked (it was healthy), and my blood check it was healthy as well, i am 17. Now i am scared that i am going crazy or be possed or be a murder or something insane like that. I am scared i always been a busy thinker since i was akid what should i do i just want to enjoy life and not worry because im only 17 years old!