Fatigue in forearm while performing forearm wrist motion

Hey! I was wondering if there is anything to be seen about my picking motion. As the title says, the whole underside of my forearm keeps feeling fatigued. I’ve tried to adjust my grip, arm placement, ‘palm’ placement, wrist height (keeping my hand ‘floating’ above the bridge as described in the pick slant primer for forearm - wrist motion. One more question, when I get this technique down, how is it possible to do mixed escape motions since since there is a downward pick slant while using this technique. Thanks in advance!