Rapid cycling is something that is experienced by some BP II patients. It means that there are more than 4 cycles of depression to mania/hypomania a year.

You also get ultra-rapid or even ultradian cycling. It just means the time between a depressive episode and manic/hypomanic episode is shorter.

Mixed episodes are not very well understood nor researched. You experience some symptoms of depression and some symptoms or mania.
It often includes anxiety and irritability