I got a concussion 3 weeks ago and have has constant headaches since. only goes away if i'm in a dark room. ?

Post-traumatic HA: Often accompanying the headache are symptoms of post-traumatic syndrome such as vertigo, blurred vision, memory impairment, reduced attention span, difficulty in concentrating, sleep disturbance, anxiety, depression, mood changes and irritability and migraine-like symptoms (dark room). See headache specialist.

Get checked: Concussions require complete rest. You should get checked by your doctor and/or neurologist. There may be treatments that you could do to help relieve some symptoms.

TTM: You are likely experiencing trauma triggered migraine, with headache and photophobia. You should see your doctor for evaluation and management. Medications that may help are amitriptyline, topiramate, depakote or inderal (propranolol).

Reducing stimulation: It is common with concussions to reduce stimulation, light, noise, even tactile to diminish ongoing symptoms. I would also continue to talk with your Dr about symptoms and plans to help you manage your days/work/school etc. You may need to take some time off to recover.