Hi
The symptoms mentioned by you have their origin in the head injury you had suffered recently. It is important to get them diagnosed and get the underlying condition treated. You should visit a consultant neurologist for a thorough examination, including blood workup, CT/MRI/Lumbar puncture.
Most head injuries are closed injuries, and may manifest no visible injury. A head injury may not cause immediate symptoms. Dizziness and headache are a common result of mild traumatic brain injury (MTBI). They may manifest as late symptoms of the injury.
You should discuss about exercise and workout possibilities with your doctor, who will be able to advise you better after examining any underlying cause. Do write in after your doctor’s opinion and in case you need any other information.
Take care
Get a brain MRI. I cannot stress the importance of this. They will be able to see more than on a regular CT. Also, you might want to consult with a Neurologist. I have had brain trauma and got the same results that you did when I collapsed and was taken to the ER. It took a couple of years, the suggestion of a brain MRI, and a consultation with a Neurologist to finally figure out part of the puzzle for me. However, I am learning more as time goes by. I'm now 10 years older and suffering from severe migraine, nystagmus, and other stuff. Don't wait to seek out more medical care, I am living proof that sometimes they overlook some very serious symptoms, and it can affect you for the rest of your life. Best Wishes.