Lightheadedness is not really a concussion symptom past the first few hours. It is common to anxiety, especially when it shows up later. Some confuse dizziness with lightheadedness.

The whiplash would easily cause some or all of these symptoms. Disturbing your inner ear could also cause them. You could have dislodged the crystals in the inner ear that help you know various head positions. If laying down helps, that could be an indicator.

Ask your doctor for a referral to a vestibular therapist. Maybe you can be put through the Epley Maneuver to try to reset the crystals in your ear.

This type of vestibular trauma can make life miserable. Just moving can make you feel lousy.