Sometimes intrusive thoughts are normal to have and are somewhat cathartic; it is imagining an act instead of doing an act and the more you try to push the thoughts out can actually make them stick around.

For example, if I tell you not to think of a penguin, you are more likely to think of the penguin.

Maybe it is just your inner primate having skull bashing urges.

Do you have a therapist? If it is really worrying you it could be worth talking to someone about it.