reoccuring anxiety cycle

everyday i develop a new fear or phobia.
usually about my health.
so far, i've thought i've had a brain tumor, heart disease,
diabetes and other things.

but i know it's just me being a hypochondriac.
then i find myself looking up the symptoms on websites,

i know i have eye strain from being on a computer alot.
it gives me headaches, dizzyness, sore eyes, makes me feel like im dreaming.

i guess this is why i think i have seriously illnesses.
then i get worried about it all, and cant breathe properly and
have anxiety/panic attacks.

does anyone know anything to help me get over this?
to stop thinking that i have illnesses,
also if anyone can reccomend stuff that makes you happy?
because latley i'm finding myself very unhappy, due to worrying and stressing
all the time, also about school family and friends.
thanks (: