Multiple Personalities Support Group
Dissociative identity disorder is a diagnosis described as the existence in an individual of two or more distinct identities or personalities, each with its own pattern of perceiving and interacting with the environment. At least two of these personalities are considered to routinely take control of the individual's behavior, and there is also some associated memory loss,...

The question is, do you have a plan when it happens, especially for times when self harm is involved.
Here is where you need a toolbox to fall back on with strategies to cope that are healthy.
Hopefully you have already spoken to the" team" about not harming the body or have some kind of contract.
Be safe and hope you will let us know what is working for you!
As a side note: rapid cycling of moods can be a symptom of other problems and should be talked to with doctor but it doesn't sound like that is your situation.