Can a broken nose 6 months ago cause headaches now even though I had surgery to fix it?

It is very likely that your headaches may be associated with nose/head trauma. It may not only be result of nose trauma and surgery but also head injury. You should address headache issue with your primary doctor and neurologist. Good luck.

 A broken nose can cause issues with the nasal bones, upper lateral cartilage, the tip, and create a deviated nasal septum. We have seen patients who have gotten a deviated septum from a nasal fracture. The source of the headaches can be from a bone spur present on the septum from a traumatic injury. It's  Important to have a CAT scan of the sinuses to rule out any chronic sinus disease going on as well.