What you are describing is me ON meds. Off meds I have full blown schizoaffective bipolar type. Meaning schizophrenia symptoms and bipolar (mania and depression) symptoms. ON meds I have mood swings. Off meds I am totally out of control with my depression and mania. Just tossing that out there. Sounds like you are talking about mood swings. Which can be part of a personality disorder such as BPD or just totally on its own as just stress related. I would look into the stressors in your life and how to cope better with them. Make sure to have a really strict sleep cycle, because I know when my sleep is off, my moods can be all over the place.