Congratulations on both flushes! You both got rid of some deadly toxins and are on the road to better health.
In regard to your husband's headache, I am so sorry that happened. It's never fun to be in pain. My first question would be what does his diet consist of on a daily basis? Does he drink a lot of coffee or cokes? The headache could have been caffeine withdrawal. The headache could also be related to toxins being released during the flush. Also, the first day of his Master-Cleanse could have been both of those things, too.