hello will19 - maybe you ought to investigate vitamin e toxicity - http://www.ihealthdirectory.com/vitamin-e/
possibly your body metabolizes vit. E in a different way than other folks. since there is more sun time in the summer - you feel like crap and become irritable and depressed.
it's just a thought and i hope it may help.
along w/ the idea that maybe you ought to move to alaska or canada - .