There MAY be a middle ground here, but again, you and husband have to be on the same page. Here's how the conversation could go:
husband: "Take your pill."
difficult child: "I want cereal."
husband (or you): "As soon as you take your pill, I'm happy to get you some cereal."
As hard as it is, try to avoid using the word no. It's not liable to get you what you want and very likely to cause a meltdown. The conversation above sets up a time progression and gets you both what you want. It's a win-win situation.
Good luck. I know this stuff is not easy.
