I used to get them pretty frequently, like one every couple of weeks. They've got way less frequent now but I still get them from time to time. Mine are pretty random too now but they seem to be more common in bright light, hot weather and when I'm dehydrated - so I definitely always try to keep water on me and drink it regularly throughout the day (like Elvenfrost suggested). It sounds dumb but I always shield my eyes from any bright lights instinctively, even if I'm wearing sunglasses. I think I'm quite sensitive to light anyway because strong light makes my eyes sting a little, so it's always good to take precautions haha.
But yeah dark and quiet spaces are the best bet - I've walked out of classes and stumbled home a few times with no vision but it's worth it to be back in bed. I know you said it's not an option for you but prescription-strength painkillers definitely made a difference for me compared to regular paracetamol/ibuprofen. Helps to stop the feeling that your head is being ran over by a truck a little more!
But yeah dark and quiet spaces are the best bet - I've walked out of classes and stumbled home a few times with no vision but it's worth it to be back in bed. I know you said it's not an option for you but prescription-strength painkillers definitely made a difference for me compared to regular paracetamol/ibuprofen. Helps to stop the feeling that your head is being ran over by a truck a little more!