I have what you describe just before migraine. Doc said it is ocular migraine. I keep getting a warning from optometrist that glaucoma test indicates pressure. So I go to GP and get diabetes test. All clear on fasting glucose.

Sometimes I just get the ocular bit and not the headache after.

The ocular migraines happen more often when the sun is lower in sky and I see it glinting off chrome bits on cars. Tend to come in the morning after drive to work. Think I have only had on at night time.

I was told not to worry about them, but I am with others here.

Get yourself looked at by GP and eye doctor.