Hi lucy,
What you are describing sounds like an aura seizure also known as a simple partial sz. whrere you smell different odours which aren't there and then the simple partial sz. may be leading into a complex partial sz. where you see different colors in your eyes, have a wicked migraine headache and often the short term memory goes down hill over time either do the the seizure meds a person takes or because the hippocampus in the brain is beginning to shrink. This is what happened to me and my neurosurgeon removed the right hippocampus of my brain. Check out this website for more info.
Be sure and write down each time this happens on a calender along with a discription by doing this the neuro may see a pattern in the time of day/night you have any sz. and what days of the month.
http://www.emedicine.com/neuro/index.shtml#seizures

www.epilepsy.com

Here's wishing you well and May God Bless You!

Sue