You may have aggravated the blood vessels at the back of your head, if so it can take a while for your body to adjust back to normal but in the meantime it won't take much to set the throbbing off again even if your bp is reducing.
Thanks for that, as you are already an experienced powerlifter it makes your results all the more meaningful. How much did you take each day?
Any thoughts as to why your deadlift didn't increase as much as squat and bench?
i expect it's someone like Nick's Strength and Power (or whatever he calls himself these days) who has never actually tried sarms not that it stops him from trying to pretend he's an authority on the subject.