Hello, If I were in your position, I would highly recommend a visit with a neurologist who will check to see if in fact, you may have suffered a concussion which nowadays is the same as a mild traumatic brain injury (mTBI). If so, then, the neurologist will be able to test your brain function and reflexes to determine whether or not you are fit to fly. The swelling on the forehead is from the traumatic injury which has produced some subdermal bleeding. This will eventually go away but will remain painful for a while yet. The ER would have likely given you instructions on medication but for the time being a cold pack of ice over that bump will likely make it feel better and help the swelling to reduce a bit. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Dariush Saghafi