It could be to bright if this is a new light.
her age? Temperature? What type of betta? Could something be leaking electrical current into the tank? Do you have an air pump vibrating. Seasons are changing, November until now is the tank getting more sunlight?
Is this a dragon scale? Years ago I had a dragon scale that had scales grow over its eyes. Was very frustrating, I believe it was a genetic defect. Keep us posted Good Luck