A month back I got a concussion from playing hockey. Didn't loose conciousness but I finished the game. About two weeks later I relapsed because of exercise (High Intensity Interval Training). Now when I play video games or watch TV my brain starts to fog up and I feel dizzy. I never had this before throughout the concussion. Is this a bad sign or a good sign? What is the best course of action?
I need to get back quickly into the flow of things because I don't want to miss too much school.

Note: I have been to the ER twice and they refused to a CT scan saying that it wont show a concussion.