I hit my head today really hard. i am havin headaches. and i feel weak sometimes. could this be a concussion?

Concussion Diagnosis: Concussion is caused by trauma to the brain. Concussion causes a constellation of symptoms including headache, confusion, nausea, dizziness, mood changes and sleepiness. You can have a loss of consciousness as part of the initial injury but this does not happen in all concussions. Treatment is rest and gradual return to activity. Contact your doctor for more details.

Depends: The effects of concussions can vary and be unpredictable. It depends on the severity of the injury. The symptoms can include headache, dizziness, vision change (blurred vision/ double vision), nausea/vomiting. If your symptoms or headache are severe, or if you have a loss of consciousness, you should get evaluated immediately.