Had them since I was 12-13.
Back then I found the trigger was chocolate - since avoiding that I've had far fewer.
Other things now trigger the same response with me - Aspartame, Acesulfame (the newer artificial sweeteners) - maybe try to avoid these.
Mostly found in diet drinks - but more lately in cheapo non-diet drinks
Apparently, it's cheaper than sugar for the same sweetening effect. It's also found in chewing gum (which is mostly sugar free).
Check the ingredients - it crops up in lots of unexpected places.
Once I get one - the only thing is the dark room, meds and about 24h to 'come back'
Then about 24h feeling totally washed out.
I hope you find the trigger for yours, once you know what to avoid it really makes a difference - well reduces the frequency - if not the severity.
best,
z