You don't know especially with a mild concussion,so it is best to seek medical help, but you can have headaches,dizziness,fainting spells and other things that is why it is best to have any head injury checked out by medical people you have to have a scan to really tell,a concussion jars your brain and just by looking you can't tell how bad it is because if left untreated your brain can and will swell...the best to you and it can be fatal.....
Having a concussion will make you very sleepy to the point that you will want to go to bed. You may have a migraine headache, double vision, dizziness, nausea, dilated pupils. Should you have any of these symptoms associated with a concussion you need to see your Dr asap.
You know you have a possible concussion. When you have double or blurry vision a sharp stabbing pain in your head. Your extremely nauseous and or throwing up. You can't sit or stand without your head pounding. You get extremely tired. You have memory loss , repeat urself etc... If I have left any symptoms out please correct me thank you. This is Nick from Washington state