Let me know if you find out anything, because I have a similar problem.
In my right eye, right about where my blind spot is, a small area will
occasionally flicker.  It comes and goes.  Seems to mostly come either
later in the day, when neck is stiff, or after physical activity.  And
when it starts, squinting and/or straining my neck will agrevate it.
The flickering looks the same as the flickering blind spots that can
accompany a migrane headache, but it doesnt last, its just a brief
flicker, that you only notice when you are looking around or like I
said after I squint or strain my neck.