Hi, I had a concussion about 4 and a half months ago. I get dizzy spells if I stand up or roll over in bed too quickly. Other than this, I was feeling fine. But, two days ago, I started with a really bad headache and now my heart feels like it s beating really hard. I m dizzy and tired as well. What do you think is going on? Could this be related to the head injury even though it was over 4 months ago? Help! Thanks...