My dad and I just went through a mandiblectomy and fibula free flap reconstruction two weeks ago. It's so hard to see your parent scared and in pain! I realize this is probably too late to help you, but my dad's nurses gave him nebulizer treatments to loosen up his sucretions so his trach wouldn't get clogged so often. He almost got out of bed once when he thought he was choking and that was terrifying. My dads surgical oncologist said that they typically start radiation between 6 and 10 weeks post surgery. Anything sooner and they worry about the wounds healing. Anything later and they worry about whatever they removed with surgery regrowing. Strength, love and healing to you and your dad.