Hi Laura,
I'm so sorry to hear that your husband has all these medical problems I do know that sleep apnea, stroke, and sometimes diabetes can cause sz. for some people. You might want to check out this website to get a lot of info. on these matters. http://www.emedicine.com/neuro/index.shtml#seizures
When your husband starts to smell odd odours that is known as a simple partial sz. (aura sz.) If he is just staring like a person daydreaming for a few seconds that's an absence (petit mal) sz.
I found that using nutra sweet (aspartame) can cause more electrcial activity in the brain which can trigger sz. for me. I found this out when I started to drink diet soda and then I had many sz. I spoke to my neuro and he told me it was the nutra sweet causing the problem and to stay away from all of the sugars like that. This also may be the reason why your husband is having migraines.
I do know that every time I get sick with a cold or virus of some type I end up having more sz. because it messes up my body chemistry and if I take a cold or sinus med it slows up the seizure meds through my blood stream.
Have your husband cut back on the carbs and protein foods and start eating foods high in fat this is known as the ketogenic diet and has been around since 1927. The diet helps stop or reduce sz. and it works great for people who have grand mal sz. Here's wishing you and your husband the best of luck and May God Bless You Both!

Sue