I had just finished 7th grade. I was taken to my PCP who thought I was crazy and then spent 3 weeks in a mental hospital before being sent to a boarding school for troubled kids. I don't know what the standard definition of "nervous breakdown" is, but I usually say I had a "nervous breakdown" during this time. From my experience, it means being not all there, somehow detached from reality. I wouldn't say crying all the time is a nervous breakdown but certainly is tumultuous and emotionally unstable.