I've been having out of character mood swings and some other things as well
Mood swings usually (from happy to sad or annoyed)
I'll cry about stupid things
feeling of failure
this has been happening on and off for about 3 or 4 months
It could be a disorder or it could be nothing but stress and hormones from being a teenager. Best to get diagnosed by a doctor.
Sounds like a sort of depression. Resort to a counselor to better your options to feel better.
Have you been sleeping okay?