i remember very vividly 7-8 year old me complaining about my stomach hurting and me crying about how i didn't wanna go to school many days and no one ever believing me. so when i went to the doctor about it they said nothing was wrong with my health and furthered my parents belief that i was faking it. turns out the whole time i had anxiety...as a 7 year old. 
that's fucked. and it just got worse from there on out lol