I sometimes get black dots or black flashes in my vision. I have had my eyes checked and everything is fine. What else could this be?

Reassurance. Sometimes an eye exam by one doc is not helpful of reassuring you that your eyes are ok. It would be wise to see a different doc, preferably an ophthalmologist who will dilate your eyes and examine the posterior part to make sure all is well. You may just have floaters (dots, stringy lines, veils) that mah well be normal. Another idea is migrainous aura that may be episodic without eye findings. .