Hi there, I am Dr. Deepak, I work in Emergency Department, where I see many patients with injury to their head. As you mentioned you had injured your head yesterday, when you fell backwards. Now you are feeling nauseated, feel light headed and slight headache. I feel you had sustained minor injury to your head, I can say that as 1. you didn t had any dizzy feeling. 2. You didn t had vomiting even though you had nausea. 3. You didn t loose consciousness. 4. You are not feeling any numbness or weakness of any one side of your body 5. You are not having any blueish discoloration around your eyes and behind the ear 6. You are not having any trouble with walking. And the most important thing is you are pretty much okay right now. If you are healthy person age 15-65 yrs and and not taking any other medication, then I feel when you had fallen you might displaced one of the small stones that is present in the ears which help us balance, It can lead to similar problem. I would suggest you to you to 1. You can wait and watch if it comes down. 2. You can try few exercises like Epley maneuver, and similar one which you can find the internet. 3. If it still persists then you can show it to an ENT specialist. Who can examine you and let you know what might be the problem. But if you are taking medication related to heart problem or having bleeding problem or age more than 65 then I would recommend you to see Doctor. Thank you Hope your concern was dealt with and hope you have a speedy recovery.