A re-occurence of pain does not necessarily mean a new injury or damage to the previous injury. Usually, it just means you did too much or pushed too hard. For me, my concussion head aches will manifest out of the blue. No triggers. No over-stimulation. They just happen. I am used to it because this has been going on for decades. They come. They go away. Sometimes, I need ibuprofen or acetaminophen. Life with PCS.