Children/young people are hard to evaluate. Are they telling the truth, are they making it up to get attention, they also have vivid imaginations and what the read and watch on TV is filled with fantasy and make believe. But without an examination it's not possible to sort out the rare but real from the common that is imagined.
One thing you can do at home is ask him to look straight ahead at an object 6 meters/20 foot away. Then observe his eyes. They should be still not moving. If they are making fine jerking movements this is called nystagmus and would require he see an eye MD. If he has no other complaints and the problem persists he would need to see an optometrist or better an eye MD ophthalmologist when the pandemic is over. If he has alarming symptoms, severe headache, fever, seems ill would need to call your pediatrician or go to ER. This does not mean something is wrong with his eyes but if it persists does require professional exam.