Post-Concussive Syndrome (PCS) is when after a "normal" amount of healing time after a concussion, 4 weeks is max; you still experience symptoms from the concussion. Maybe your symptoms aren't getting any better from when your concussion initially occurred. PCS can last for weeks, months, a year, and for some people they will have lingering symptoms for the rest of their life.
That's more of the technical definition but as a patient with PCS I’ll give you my experience. I had my initial concussion and waited everyday for the horrible all the time headaches, migraines light sensitively, noise sensitivity, dizziness, increased anxiety, sleep issues, blurred vision, and nausea to subside.
All I could do was lie in the dark all day I couldn't handle my phone light, ant audio stimulation nothing. Three weeks out I hadn't made much progress and could barely read my vision was completely disrupted from my injury. At five weeks nothing had changed and I felt like I was living a nightmare waking up every morning with a headache knowing all day I would just sit in the dark in pain until I would go to bed again with another headache, if I pushed it too hard I would get a migraine. I couldn't drive, let alone even go into Rite-aid to pick up my medications because to me walking indoors the music felt as though it was blaring, the lights were so bright they came through my sunglasses burning into my head. The simple chatter and clacking of other customers made my brain hit a wall where it just stopped and I just felt unable to move from the pain and nausea set in to spark an even worse pain.
The thing people don't understand with brain injuries is that unlike a broken ankle it's hard to just rest it. Even sitting in the dark or sleeping isn't resting your brain completely it still needs to be functioning at some level all the time to keep you alive. Doctors don't even really understand Post-Concussive Syndrome very well. Specialists couldn't tell me when exactly my brain was or wasn't done healing and all they could say was it "most likely will get better but we don't know when could be 3,6,9 months or more we just don't know and there is no treatment." This left me feeling completely hopeless not knowing when I would get my life back.
The truth of the matter is there is treatment, it's just very specific and new and upcoming. Things like ocular therapy, neurofeedback, chiropractic- neurologist, craniosacral therapy, and even some occupational and physical therapist are trained to help. If you or a loved one has PCS try your best not to lose hope, trust me I know it's hard. Surround yourself will people and providers who will support you in your journey. As well as realize you are making progress just sometimes it's so small you don't even notice it.