Have you tried journalling? That might give you some insight into what is causing your mood reactions, even a mood diary where you chart every single time you have a "mood" and what was happening or just happened for you at that time. If you do this for long enough, I think you would be surprised at what triggers you discover.

If you never deconstruct what your triggers are, you will never stop "rapid cycling", is that really how you want to live the rest of your life? Meds are largely ineffective for people who are reacting to triggers, some work for some people but good therapy is what you really need to stop this kind of "cycling".