Hi,
How are you? It is possible that you have acephalgic or silent migraines. You experience the aura in migraines such as nausea, vomiting and sound and light sensitivities but do not progress to the headache phase. The treatment is the same as with migraine headaches. If it persists, you may need to have thsi checked by your doctor for proper management. Take care and do keep us posted.
it sounds perfectly possible to me that you're having silent migraines, where you experience some of the symptoms of migraine (being the aura/flash) but not the typical head pain. My mom only gets the aura, and never the pain, so yeah, it's possible.
I'd let your GP know if it's been there that long.