ADVICE APPRECIATED: sporadic depressive episodes

TW: discussion of depression and su*cide ideation. i'll try to keep it as non-detailed as i can, but please make sure your own well-beings are okay!

i have no official mental illness diagnoses, although i did try to get one for gad last year because it was pretty clear i have it. i don't think i have a depressive disorder, but sometimes i'll get really extreme depressive episodes. each episode usually lasts around 3-4 days at most, but on average it's just a day or so. i do have some symptoms of depression on a regular basis, most likely from stress, but during one of these "episodse," it gets to the point where it's so bad, the su*cide ideation is elevated to a point where i am in a place of danger. it's really, really scary to me because i have little to no control over my emotions or thoughts during these moments, and when everything has settled down i get really upset because i'm scared one day i'll really end up going through with it during an episode. i'm in a very stressful point of my life right now, but i've never had sporadic, intense mood declines like this. i don't know what this is. does anyone know what might be happening to me?