Well, yes, it is possible to have red eyes after a concussion. As we know that a concussion is an injury that affects the way the brain functions. And you should know that it is typically associated with blows to the head. And according to some researches, concussions often result in immediate confusion and loss of coordination followed by bouts of nausea and vomiting. But also, it can lead to red eyes, sensitivity to light, and other symptoms. When it occurs, you may not need to worry about it too much. Maybe it will just disappear with time. But if it still exists, just go and have an exam.
Yes, it is very common symptoms from a concussion. A concussion is usually describing injuries to brain, which might be caused any serious blunt force on the head. Concussion especially describe these injuries to brain which don't cause any bleeding in the skull, so it is not lethal. Some common symptoms associated with a concussion include blurry vision, headache, nausea or vomitting, loss of consciousness temporarily, confusion, loss of some memory or perseverating. As to bloodshots in eyes, we might get them easily. Simply eye strain, or very common daily movements with force would cause these bloodshots in eyes, because the capillaries in eyes are very delicate and fragile. Just weight lifting might cause the bloodshots too. So you can imagine, a strong and serious blunt force on the head would easily cause some bloodshots. But as it comes easily, it goes off easily too. Bloodshots can heal up within days without requirement of any treatment. Don't worry too much.
It is normal for you to get red eyes after concussion because the brain damage will cause the damage of the eyes nerves. Your eyes may get the bloodshot because of the sudden increasing eye pressure and unstable eye nerves. You should use some home remedies or medical are to treat the red eyes to let them get recovery. You'd better go to the hospital to have the check on the brain. Your red eyes could be used the warm compress to let them feel comfortable. You could also use the eye drops to release the eyes. You'd better treat the eyes carefully. Or else, your eyes could cause another eye infection. You should treat them well.