depression !

hi !
i am 21 year old boy .i am facing a very strange feeling from the past 2 months i cant able to sleep in nights .thinking about worst situations .i am very possesive about my healthe .whenever i get some small disease or wound i feel that this could be a high disease thinking it for all night .
pleaseeeeeeeee tell me how to get rid of  it ! i think i will go mad one day