Mental Illness?

Umm, so I’ve been depressed off and on for the past, I wanna say, 10 months. I swear, it’s like clockwork, I will be feeling like utter garbage, and then a few days later I’m fine. Then, the next day, I go back to being worthless. This cycle has led me to various forms of sh and several mental breakdowns. I just want an opinion about what this sounds like to someone I won’t have to look in the eyes.