the drying process isnt the only thing you have to take into consideration here. there is also a CURING process that i would be willing to bet both of you have skipped all together.
you should store fully dried buds into mason jars and remove the lids for about an hour every day for about the next month or three.
fully "cured" buds will burn smooth grey ash.
maybe research curing your harvest, its not about flushing your plants at all. you can feed until the day you harvest, as long as you dry and cure your buds properly you wont have the issue your having now.
+rep if it helps.