Dealing with Random Depressive Episodes

Does anyone know what to do about random depressive episodes? I haven’t actually been diagnosed with any mental health problems but I’m fairly sure I do have some and know when it started. Like I’ll be totally fine for a few hours (or days, it varies) and then suddenly I am tired, easily aggravated, and overall just really depressed. I start having no motivation and stop doing stuff I know should be doing like taking care of myself or not liking stuff I normally do while having frequent break downs and stuff. I honestly hate it all and I’ve been dealing with it for a few years now. Any suggestions…?