Heading the ball is seriously risky. My academic world was forever changed by heading the ball. If you ever return to playing football ( I take it you mean soccer football, not American football), you should consider the risks and avoid any head contact.

Your brain has been injured and will never regain its full pre-injury condition. Many find that their head has become very sensitive to any impacts.

You will likely find that there are triggers that cause your symptoms to roller coaster. Physical exertion, emotional exertion, chemical stress (alcohol and such) and such can cause a return of symptoms. You need to watch to find your own threshold of these activities.