(Mental health question) How do I find motivation?

Sorry for wall of text

Throughout a typical year, in school and out, I go through ups and downs. For a short time, I’m happy. I get things done, I’m motivated in school, home, CAP, etc.

And then suddenly, for reasons I can’t explain, I get super depressed. 90% of the time, nothing bad has happened. My school work load is manageable, I’m not stressed at home or CAP, I just suddenly feel really really down. I don’t want to get out of bed, do homework, nothing. I end up falling behind in school and I don’t know what’s causing this.

Sometimes the ups last a few days, sometimes a few months, same with the downs.

I have been diagnosed with depression and anxiety. I was put on meds, but no longer take them. Even on the meds I was going through these ups and downs. Last time I took the test for depression, my doctor said I scored a 3 which was the lowest score for me (which was good). For anxiety, he said I was still above average. I can’t remember exact score but it was around 45

School has only been in session for about a month, and I really don’t want to start falling behind. I just can’t find the motivation to do anything. I’m forcing myself to go for walks, go to CAP and to do homework.

I’m not sure why I keep going through these ups and downs. They are sudden, and they feel drastic. Like one day I’m super happy and the next I’m on the verge of crying and I’m laying in a dark room.

I would really appreciate any advice you guys have.