Fainting ?

I'm just over 11weeks had 2 slices of toast around 10:30 we then went to morrisons around about 1:30... Normally I'm ok but for some reason I got started feeling really out of breath on the way.. We sat down and had a rest and then set off again whilst walking around I started getting out of breath again but this time I was gagging too! We rushed to finish our shopping and whilst at the check out i almost threw up followed by going weak at the knees and nearly hit the deck .... My husband had to go run get me a banana to eat and kept saying how pale I'd gone ... Took me like 15 mins to come round and feel ok again after Id eaten the banana . Any one else had anything like this happen?