I am the queen of meltdowns at school. School actually causes MORE anxiety for me than anything, and so just before I had to drop out I was basically going to school and then either having to head straight to the counselor (they had them IN my college, thank goodness!) or trying to calm myself from a near panic attack while hiding in a washroom stall!
Is there no one to talk to at the school? I am not sure how it works in the US, but in Canada every school has counselors to speak to and at the very least they know how to direct you to a therapist outside of school.
I have also been to the ER to help me find someone to talk to during a crisis, but save that for a last resort because they seem to get great joy out of trying to put you on suicide watch, even if you aren't suicidal and tell them so, lol.
Do you have a family doctor? That works too...
"I don't wanna be lonely, I just wanna be alone..."