This is exactly what is happening with mine.
Below is from a forum about seizures.
I have been having aura type things going on for a couple years now. I went to a neurologist who told me it was a version of a seizure. I’ve never had an actual seizure. But, the auras really freak me out. It always starts with a strange smell and feeling, then deja vu, then sweating and upset stomach, then it’s over and I can’t remember any of the visions I was seeing (deja vu scenes) in my head. And I usually end up with a headache and needing to poo. Ha. It usually always makes me cry after too. They’re annoying, but I’m grateful I don’t have physical seizures.
hi when you say a strange smell what sort of smell? I’ve had these funny turns for a couple of years now and life been shopping and all of a sudden I can smell a really strong smell but none else can then this weird sensation comes over my body, I feel really faint shaky and my heart is pounding etc but I dont know what is happening.
tbh i dont get a strange smell but i get the deja vu feelings which leave me with same feelings as you like the faint feeling and heart racing and shaky with strange feeling through my body. it leaves me quite tired after. i also get feeling of weird vision almost like wjen your in a panic and everything seems surreal and cloudy. i dunno if its seizures or anxiety but i have been tested amd no seizure has shown so who knows but i am scared
wow this sounds just like me and om the same no idea if anxiety or something else. well I hope you get some answers soon 
the doctor and neurologist says its anxiety but i just cant believe him coz it happens so often and i read seizure websites and my symptoms match.
i just dont see how anxiety xam cause these types of symptoms