That doesn’t seem like an ear infection, but trauma injury might be the reason. Is she eating and drinking, and active? If so, I would just keep an eye on her. If there is any grey color to the wattle or comb, and she seems sick, I would do some research on fowl cholera.
Look for any ticks on her or around the coop. They can bite and it could be bruised from the anticoagulant ticks inject. But it could also be from a peck or injury. Check her ear for any drainage or gunk as well.