For the past 5 months I've been intermittently seeing flashes of light in my peripheral vision, as if somebody has just taken a flash photo of me or there was a sheet lightning storm. It's very confusing because I don't realise it's not actually there until I see there's no camera and it's not stormy, can't hear fireworks etc.

Lately it's become quite bad and I usually get a headache and feel disorientated afterwards. Is this something I should be concerned about or is it eye strain / something that will go away? I'm afraid to go to the doctor again unless it's absolutely necessary. Or is this something I would be better off seeing an optometrist about, if it doesn't go away?